The common mrc cache driver allows to save the raminit training
results to a separate fmap region which is more manageable than a
cbfsfile.
Change-Id: I25a6d3fe5466d142e3d10429a87b19047040c251
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/23484
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>