Fix a bug of GPIO falling-edge interrupt for tiva

userleds: Don't select ARCH_LEDS with BOARD_CUSTOM_LEDS, otherwise we can't use the board_userled* functions

Stm32l4_update_rtc_impl

use INITS flag to avoid magic reg value to detect power up reset state of rtc
correct a problem clearing interrupt flags (they weren't) which prevented an alarm from ever being used more than once per reset cycle

Fix a copy and paste error concerning the CAN driver. In the file sam_matrix.h the define SAM_MATRIX_CAN0_OFFSET is set to the wrong value.

Error is only triggered if the global variable g_mcan0_msgram is located in RAM at an address beyond 0x20400000 + 0x0000ffff. In this case all send CAN messages have the length zero and the CAN-ID is zero as well.

Fix typo in variable name in serial BREAK logic.  Review other serial implementations for similar naming problems.

when setting an alarm, ensure that the respective alarm triggered flag is reset, because the alarms are edge-triggered interrupts

fix nasty bug in ISR handler, where interrupt was not properly acknowleged (write to CR instead of ISR, as intended).  Also, minor, set the LSI prescaler values more appropriately (though not critical since LSI is so low precision anyway).

userleds: Don't select ARCH_LEDS with BOARD_CUSTOM_LEDS, otherwise we can't use the board_userled* functions

correct the RTC_ALRMR_ENABLE value, it needs to ignore the date/dow component since that is not set.  Also, the prescaler value for HSE (which presumes 1 MHz, anyway) had transposed digits.

UAVCAN: Update version

add unique id function to arch, modded board to support unique id boardctl

support for HSE and MSI clock sources; prelude to USB

booboo in config sanity check; wasn't preventing insanity

stm32l4-disco boardctls for qspi memmap; bugs found along the way

add board ioctls for allowing user application to cause qspi memory mapped mode to be engaged and disengaged.  Also partitioned qspi flash for filesystem and other purposes (eventually xip).