Enable separate MRC cache for recovery mode. This requires change in
flash layout to accomodate another region for RECOVERY_MRC_CACHE.
BUG=b:37682566
TEST=Verified following scenarios:
1. Boot into recovery does not destroy normal mode MRC cache.
2. Once recovery MRC cache is populated, all future boots in recovery
mode re-use data from the cache.
3. Forcing recovery mode to retrain memory causes normal mode to retrain
memory as well.
Change-Id: I4c748a316436001c5a33754084ab4a74243e21df
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/19457
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
