drivers: flash: stm32 ospi flash driver for stm32l4plus mcus

Adaptation of the ospi nor flash driver for stm32l4 plus
where the peripheral is slighty different.
Configure the OSPIM peripheral for mcu embeddingthis peripheral
in front their octospi instances.
Add LOG for read access command like for write access.

Signed-off-by: Francois Ramu <francois.ramu@st.com>