Activate FLASH hal support on 2 STM32 boards
Activate FLASH hal support on 2 STM32 boards

The generic Flash support for L4 and L0 families is already there,
but was not activated by default on 2 recentely added boards:
DISCO_L475VG_IOT01A and DISCO_L072CZ_LRWAN1
This is done now.

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