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.

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).

bug in smart.c; return code of smart_scan not checked, can cause success result in failure case, leading to 'dev' pointer being invalid.

add configuration options to allow SRAM2 to be used for heap, or not at all, and to zero-init it on OS start, or not at all.

add configuration options to allow SRAM2 to be used for heap, or not at all, and to zero-init it on OS start, or not at all.

QSPI DMA support in STM32L4, and DMA fixes...

fixed missing DMA peripheral selection and some header defines, updated various comments to be accurate