PTY: Add ioctls to support locking and unlocking of the slave.  LIBC: Add implementation of unlockpt()

PTY: Added PTY IOCTL command definitions.  Add support for TIOCGPTN.  LIB: Implement ptsname() and ptsname_r()

Correct some Make.defs problems for qemu-486 config

Fix a bug of tiva i2c ports configuration

Prototype versions of ptmx/pty suppoprt.  Still under developement; not yet hooked into build or configuration system.

Per documentation SAM4S and SAM4E have the BMR register values
as they are already defined. No need for chip specific values.

In addition:
 - CONFIG_ARCH_CHIP_SAM4s has wrong lower case 's' so the definitions would
   not be used anyways for SAM4S builds.
 - TC_BMR_TC2XC2S_TIOA2 does not make sense. There is no way to loop back
   TC2's TIOA2 into itself.

SMART MTD layer: Fixes freesector logic error when sectorsPerBlk=256, adds DEBUGASSERT for invalid geometry and additional memory debug logic.  Also fixes the dangling pointer on error bug.

If CONFIG_SPIFI_SECTOR512 undefined, lpc43_bwrite doesn't do actual write (probably copy/paste errors). Still not sure about current state of lpc43_spifi implementation, but for me NXFFS works with this patch.  From Vytautas Lukenskas.

I'm using syslog through ITM. In this case syslog_channel function is call before ram initialisation in stm32_clockconfig. But syslog channel uses a global variable that is reset to default by the RAM initialization.

port foward bugfix from stm32 of oneshot timer

This commit solves a problem which causes data loss while sending data via USB. This problem is caused by an incorrect handling of the endpoint state in the USB driver sam_usbdevhs.  This leads under some circumstances to situations in which an DMA transfer is setup while a previous DMA transfer is currently active. Amongst other things I introduced the new endpoint state USBHS_EPSTATE_SENDING_DMA for the fix.

To reproduce the problem, I used a program which send as many data as possible via a CDC/ACM device and verified the received data on the PC.

Kinetis and Freedom-K64F: Remove unused configuration variable; fix some compile issues; SDHC is now enabled in the nsh configuration (but does not work)

STM32L4 Serial: Remove some STM32Fxxx conditional logic; fix a link error resulting from an over-aggressive rename.