drivers: flash: stm32 ospi flash driver the correct erase instruction

Use the most adapted instruction for the sector erase command
It can be 0x20 or ox21 or 0x21DE in octo - DTR mode.
The value is given by the SFDP table and  filled in the erase_types
 table the during the SFDP discovery process.

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