feat(intel): enable SDMMC frontdoor load for ATF->Linux

SDMMC is 1 of the boot source for Agilex5 and legacy products.
By enabling this, ATF is able to read out the DTB binary and
loaded it to DDR for Linux boot.

Change-Id: Ida303fb43ea63013a08083ce65952c5ad4e28f93
Signed-off-by: Jit Loon Lim <jit.loon.lim@intel.com>
Signed-off-by: Sieu Mun Tang <sieu.mun.tang@intel.com>
6 files changed