feat(plat/imx/imx8m/imx8mp): enable Trusted Boot

This patch enables Trusted Boot on the i.MX8MP with BL2 doing image
verification from a FIP prior to hand-over to BL31.

Signed-off-by: Ying-Chun Liu (PaulLiu) <paulliu@debian.org>
Change-Id: Iac1d1d62ea9858f67326a47c1e5ba377f23f9db5
3 files changed