- init the led pin as output (like other HALs)
- reduce sdio dma priority to normal.. highest is never the best...
- allow fsmc only on compatible STM32F1 (like HAL fsmc)
- fsmc: remove an useless C style cast
Adding files for STM32F1 HAL based on libmaple/stm32duino core.
Current persistent_store uses cardreader changes to be sent in separate
commit, but could be changed to use i2c eeprom.