clk: stm32mp25: implement clock check security function

clk: stm32mp25: implement clock check security function

Check clock security to avoid access at boot time.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@foss.st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: Lukasz Majewski <lukma@denx.de>
Cc: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>