arch/arm/src/stm32: Add internal pull-up option for SDIO pins (also picks up an unrelated change to a README.txt file)

This commits adds initial support for the Kinetis Freedom-K28F board.  Not you ready for prime time.

Squashed commit of the following:

    arch/arm/src/kinetis:  A fixes from first (unsuccessful) attempt to build the Freedom-K28F configuration.
    configs/freedom-k28f:  Add basic board support for Freedom-K28F.  Initial commit is basically just the Teensy-3.x brought up to date and with name changes.

This commit brings in basic support fo the i.MX RT 1050 'crossover' SoC.  The basic support is complete and compiles without error, but is still untested.

This port was the joing effort of Janne Rosberg, Ivan Ucherdzhiev, and myself.  I give credit to Ivan for the kill because he is the one to held on to the end.

Squashed commit of the following:

  Author: Gregory Nutt <gnutt@nuttx.org>
    configs/imxrt1050-evk/scripts:  Add section to linker script to handle the case where RAMFUNCs are enabled.  RAMFUNCs appear to be enabled in the default configuration ... they probably should not be enabled.

  Author: Ivan Ucherdzhiev <ivanucherdjiev@gmail.com>
    arch/arm/src/imxrt:  imxrt_lowputc.c is finished. Now everything needed for the initial port is done and ready for testing.
    arch/arm/src/imxrt:  Add logic to imxrt_lowputc.c.  Still incomplete.

  Author: Ivan Ucherdzhiev <ivanucherdjiev@gmail.com>
    arch/arm/src/imxrt:  Add serial support.  configs/imxrt1050-evk:  Add linker script.

  Author: Gregory Nutt <gnutt@nuttx.org>
    arch/arm/src/imxrt:  Add initial cut at imxrt_allocateheap.c

  Author: Ivan Ucherdzhiev <ivanucherdjiev@gmail.com>
    arm/arm/src/imxrt:  Completes all definitions for PADMUX, CTLMUX, and IOMUX_INPUT and mapping tables on imxrt_gpio.c and imxr_iomuxc.c.
    arch/arm/src/imxrt/chip:  Add definitions for IMXRT_PADCTL and IMXRT_PADMUX registers.  Only the IMXRT_INPUT definitions in this commit.
    arch/arm/src/imxrt/chip:  Add more IOMUXC register definitions.

  Author: Gregory Nutt <gnutt@nuttx.org>
    configs/imxrt1050-evk:  Add STRIP definition to Make.defs.
    arch/arm/src/imxrt:  Bring in i.MX6 memory configuration settings.
    arch/arm/src/imxrt:  Remove call to non-existent imxrt_gpioinit() from imxrt_start.c.
    arch/arm/src/imxrt:  Bring in incomplete imxrt_iomuxc.c file from i.mx6.
    arch/arm/src/imxrt:  Add first cut at GPIO interrupt logic.
    arch/arm/include:  Add definitions to support a second level of GPIO pin interrupts.

  Author: Janne Rosberg <janne.rosberg@offcode.fi>
    arch/arm/src/imxrt:  Add imxrt_wdog.c/.h

  Author: Gregory Nutt <gnutt@nuttx.org>
    arch/arm/src/imxrt:  Port SAMv7 interrupt logic to imxrt_irq.c.
    arch/arm/src/imxrt:  More clarification of the start-up memory map.
    arch/arm/src/imxrt:  Some mostly cosmetic clean-up to the imxrt_start.c file that was so rudely taken from the SAMv7.
    arch/arm/src/imxrt:  Add imxrt_start.c.  Initial commit is the the SAMv7 startup logic with name changes.

  Author: Ivan Ucherdzhiev <ivanucherdjiev@gmail.com>
    arch/arm/src/imxrt:  Adds a few IOMUXC register definitions.

  Author: Janne Rosberg <janne.rosberg@offcode.fi>
    arch/arm/src/imxrt:  Add imxrt_clockconfig.c/.h
    configs/imxrt1050-evk:  Add clock configuration definitions to board.h
    arch/arm/src/imxrt:  Fix CCM register name; Fix doubly defined in LPUART bit field.
    arch/arm/src/imxrt:  Add analog defines to CCM register definition header file.

  Author: Gregory Nutt <gnutt@nuttx.org>
    arch/arm/src/imxrt:  Bring in GPIO C files from i.MX6.  Things are in disarray now because that GPIO logic depends on IOMUXC logic which is not yet in place.
    arch/arm/src/imxrt:  Add a few more GPIO definitions to make the header file compatible with i.MX6
    arch/arm/src/imxrt/chip:  Add GPIO register definition file.

  Author: Janne Rosberg <janne.rosberg@offcode.fi>
    arch/arm/src/imxrt:  Add DCDC register definitions.
    arch/arm/srch/imxrt: Add CCM register bit definitions

  Author: Gregory Nutt <gnutt@nuttx.org>
    Purely cosmetic
    arch/arm/src/imxrt:  Add system reset controller register definition header file.
    Embarassingly trivial change left in compiler.
    arch/arm/src/imxrt:  Finishes i.MX RT1050 LPUART register definition header file.
    arch/arm/src/imxrt:  Beginning of an i.MX RT1050 LPUART register definition header file.
    Some trivial things

  Author: Janne Rosberg <janne.rosberg@offcode.fi>
    arch/arm/src/imxrt:  Add imxrt_wdog.h
    arch/arm/src/imxrt:  Add initial imxrt_ccm.h

  Author: Gregory Nutt <gnutt@nuttx.org>
    Trivial update to README.
    arch/arm/src/imxrt:  The i.MX Rt implements 4 bits of interrupt priority, not two.  Thanks, Janne.
    arch/arm/src/imxrt:  Fix some initial compile issues.  Still a long way from complete, but there is a buildable environment now for the imxrt1050-evk.
    configs/imxrt1050-evk:  Add an initial NSH configuration for testing.
    configs/Kconfig:  Hook the i.MX RT 1050 board configuration into the NuttX configuration system.
    configs/imxrt_evk:  Add the framework for i.MX RT 1050 board support.
    arch/arm/src/imxrt:  Bring in a few more files from LPC54xxx.
    arch/arm/src/imxrt:  Bring in imxrt_clrpend() from the LPC54xxx.
    arch/arm/src/imxrt:  Bring in Cortex-M7 SysTick setup from the SAMv7.
    arch/arm/src/imxrt:  Add a few easy files.
    arch/arm/src/imxrt/chip:  Add memory map header files.
    arch/arm/src/imxrt:  A few basic files to start the port to the i.MX RT 1050.

Remove all support for the CC3200 and CC3200-Launchpad.  This was a port that was started but never completed.  What good is partial CC3200-Launchpad board support with no wireless support?

Squashed commit of the following:

    Remove final references to CC3200 from the repository.
    arch/arm/include/tiva:  Remove all CC3200 support.
    arch/arm/src/tiva:  Remove all CC3200 support.
    configs/cc3200-launchpad:  Remove the board support directory.

This commit removes all support and all references to the Spark board and to the CC3000 wireless part.

Squashed commit of the following:

Author: Gregory Nutt <gnutt@nuttx.org>
    Fix a few remaining refereces to cc3000.

Author: Alan Carvalho de Assis <acassis@gmail.com>
    drivers/wireless/cc3000: emove the driver to support CC3000 because it doesn't use the USRSOCKET

Author: Alan Carvalho de Assis <acassis@gmail.com>
    configs:  Remove board support to CC3000 from all relevant configurations.

Author: Gregory Nutt <gnutt@nuttx.org>
    configs/spark:  Removes Spark board configuration.  Still available in the Obsoleted repository.  This is preparation for removal of CC3000 support by Alan Carvalho de Assis.  If there is no CC3000 support, then there is no purpose in supporting the Spark either.

    configs/flipnclick-pic32mz:  Switch the serial console to UART4.  Clean up some minor issues the LED options.
    configs/flipnclick-pic32mz:  Add support for two on-board buttons:  T1 and T2.
    configs/flipnclick-pic32mz:  Adds basic board support for the Mikroe Flip&Click PIC32MZ board.  Initial commit is just the configs/pic32mz-starterkit with some name chanages.

    configs/flipnclick-sam3x:  Add support for the 4 user-controllable LEDs on the board.
    configs/flipnclick-sam3x:  Add board support for the Mikroe Flip&Click SAM3X.
    configs/arduino-due:  Update this old configuration so that it is structured a little more like recent board support.

arch/arm/src/lpc54628:  With these changes, the LPCXpresso-LPC54628 NSH configuration is fully functional.  Also adds a README file for the board.

configs/xtrs:  Removed the XTRS configuration This was an unverified port of NuttX to a TRS-80 simulator.  It was removed because (1) it is, as I said, unverified as well as unsupported, and (2) the TRS-80 simulation is a sub-optimal platform.  That platform includes a 16-bit ROM image and only a 48Kb RAM space.

configs/mx1ads:  This commit removes board support for the mx1ads board.  That board support was never completed and I no longer even have the hardware.  The unfinished board support is still available in the Obsoleted repository if anyone would ever like to resurrect it.

    BCM2708:  Add enough infrastructrue (more stubs) to get a clean compilation of the Pi Zero configuration (with many undefined things at link time).

    BCM2708:  Add basic interrupt handling logic

    BCM2708: Add interrupt register definitions.

    BCM2708:  Add irq.h header file

    BCM2708/Pi zero:  bcm_boot.c and bcm_memorymap.h now compile.  Added pizero linker script.

    BCM2708/Pi Zero:  Add Make.defs needed to build.

    arch/arm/include/bcm2708, arch/arm/src/bcm2708, configs/pizero:  Add some basic build and configuration logic.

    configs/pizero:  Add some basic structure of the Rasperry Pi Zero port.

    Created directory configs/pizero.  Nothing there now but a README.txt file.

    Add initial boot.c and memorymap.c files
    Author: Alan Carvalho de Assis <acassis@gmail.com>

    Add AUX/UART/SPI registers definition
    Author: Alan Carvalho de Assis <acassis@gmail.com>

    Pizero GPIO registers
    * Initial commit to add GPIO definitions
    * Add remaining GPIO registers definition
    Alan Carvalho de Assis <acassis@gmail.com>

    BCM2708 memory map:  Add VBASE defintions; fix VCSDRAM address per Alan; move all virtual address to the bottom of the file to avoid confusion -- top is all physical address; bottom is all veritural address.

    Add initial memory map to BCM2708/BCM2835
    Alan Carvalho de Assis <acassis@gmail.com>

Build System:  It is no longer necessary to have a unique Make.defs file for each configuration.  A board may share a common Make.defs file in the scripts directory.

configs:  Add readme for B-L465E-IOT01A Development kit.  This port is currently under consideration (but may not actually happen)