skylake: FAB3 Adding Support for various SPD.

This pach enables memory configuration based on PCH_MEM_CFG
and EC_BRD_ID.

BRANCH=None
BUG=chrome-os-partner:44087
CQ-DEPEND=CL:293832
TEST=Build and Boot FAB3 (Kunimitsu)

Change-Id: I7999e609c4b0b3c89a9689ee6bb6b98c88703809
Signed-off-by: pchandri <preetham.chandrian@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/293787
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
7 files changed