feat(st): add decryption support compilation on STM32MP13

New files are created to test the compilation of STM32MP13 platform
with DECRYPTION_SUPPORT=aes_gcm and ENCRYPT_BL32=1.
This missing configuration was seen with the TF-A patch correcting
a compilation error [1].

[1] ("fix(st): include utils.h to solve compilation error")

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I7dc2964abf1797e3d2686f7d546128c8cf93bbcb
3 files changed