refactor(plat/st): rework TZC400 configuration

Add new static functions to factorize code in stm32mp1_security.c.

Change-Id: Ifa5a1aaf7c56c25dba9a0ab8e985496d7cb06990
Signed-off-by: Yann Gautier <yann.gautier@st.com>
1 file changed