Add supprt for STM32L4 flash driver
Add supprt for STM32L4 flash driver

No loader yet, but we can erase!

braincorp/stlink,gtalusan/stlink,trigrass2/stlink,fedorcomander/stlink,simonjwright/stlink,simonjwright/stlink,swegener/stlink,gtalusan/stlink,swegener/stlink,trigrass2/stlink,braincorp/stlink,fedorcomander/stlink