drivers/flash: stm32l5: Adding flash driver for stm32l5x series

This commit adds flash driver in non-secure mode for stm32l5x
series with icache enabled. This commit also adds a flash
programming error status check applicable for all platforms
except stm32f1 series.

Signed-off-by: Krishna Mohan Dani <krishnamohan.d@hcl.com>
4 files changed