add support for undef of STM32 lines and DMA_NOMAP
add support for F103 running at 24Mhz
add f103 variants of iofirmware
reduce memory usage in iomcu for new model
correct pwm output reporting
split iofirmware into config + mcu to allow f103 definition
don't enable non-existant timers on F103
this zeros-watchdog was caused by a SPI DMA error on STM32F405:
https://discuss.ardupilot.org/t/crash-with-4-2-0-beta-and-4-3-0-daily-bdshot/83297
we had incorrectly left these internal errors enabled when asserts
were not enabled. That led to a osalSysHalt()
without these we get an spi_fail internal error, caught by the
SPIDevice code