sim/configs/fb:  Add a configuration for non-graphical testing of the frambuffer character driver using apps/example/fb

drivers/video/fb.c and include/nuttx/video.fb.h:  Some improvements and fixes from early testing sith the sim/fb cnofiguration.

latest updates on lc823450

* arch/arm/src/lc823450: Conform to the NuttX coding style

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* arch/arm/src/lc823450: Merge the latest fix in lc823450_rtc.c

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* arch/arm/src/lc823450: Add ADC driver

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* arch/arm/src/lc823450: Add watchdog driver

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* configs/lc823450-xgevk: Enable ADC and watchdog driver

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

Approved-by: Gregory Nutt <gnutt@nuttx.org>

drivers/video/fb.c:  Add support for LCD drivers that use a simulated framebuffer and must receive explicit notification when there is an update to a region in the framebuffer.

    drivers/video/fb.c:  Framebuffer driver is code complete but as of yet untested.
    drivers/video/fb.c:  Add framebuffer character device.  This is basically only the framework for the driver; a lot of logic is still missing.

Master

* smps.c: fix error messages

* stm32f33xxx_hrtim.h: fix definition

* stm32_hrtim: fix pclk calculation

* stm32_hrtim.c: cosmetics

* smps.h: cosmetics

* add upper-half driver for high power LED driver (powerled)

* stm32f334-disco: beginning of lower half driver for high power LED (powerled)

Approved-by: Gregory Nutt <gnutt@nuttx.org>

:Remove CONFIG_NET_6LOWPAN_FRAMELEN.  In this case where multiple radios are support3d, this may not be a constant.  6LoWPAN now always queries the driver to get the maximum frame length.

6LoWPAN: Remove the option to disable fragmentation support.  Two reasons:  (1) First fragementation is always required becaues IPv6 requires an MTU of 1280 bytes.  The is no application use case that can work without fragmentation support.  And (2) it greatly reduces the complexity of the code.

6LoWPAN/Radio:  Rename radio property sp_pktlen to sp_framelen.  Add 6LoWPAN utility to get the max frame length (not yet hooked in)

6LoWPAN: I believe, based on RFC review, that with the last multicast change, the NuttX 6LoWPAN is now compliant with RFC 6282.

Update/fix last commit:  On some STM32's, the CSR regiser is 18 vs. 16 bits wide.  Need to use 32-bit register accesses.

sem_open() should return SEM_FAILED on any failures.  This is change change in the POSIX specification since the original sem_open() was written so many years ago.

STM32L4: ADC, Kconfig small changes

* STM32L4 ADC: port analog watchdog ioctls from the Motorola MDK

* STM32L4: Kconfig: add some L486 and L496 chips, remove duplicates

Approved-by: Gregory Nutt <gnutt@nuttx.org>

waitpid():  Corrects two problems when CONFIG_SCHED_HAVE_PARENT+CONFIG_SCHED_CHILD_STATUS are enabled:  (1) Was erroring out if the waited for task had already exited, and (2) was not freeing resources when a wait was completed.

Master

* stm32f33xxx_hrtim.h: add some comments

* stm32_hrtim: add burst mode configuration, rename some definitions

* smps.h: add private data to the smps_s structure

* stm32_hrtim: cosmetics

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Kinetis: First cut implementation of the alarm read function.  Pretty simple because the Kinetis RTC is just a 1Hz counter.

Correct naming of fields in struct alm_rdalarm_s.  Should not be the same as the corresponding fields of struct alm_setalarm_s.  The whole purpose of that naming convention is to keep the field names unique.

Add hooks for Boris Astardzhiev's RTC change for STM32L4 to Kinetis. Lower level logic not yet implemented.