arm: stm32mp: move the get_otp helper function in bsec

As the get_otp() helper function in bsec are common for all STM32MP family,
move this function in bsec driver

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
3 files changed