northbridge/intel: move mrc_cache definition into a common header

The mrc_cache definition and the struct mrc_container are the same
over all intel platforms.

Change-Id: I128a4b5693d27ead709325c597ffe68a0cc78bab
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Reviewed-on: https://review.coreboot.org/13998
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/northbridge/intel/haswell/raminit.c

@@ -22,6 +22,7 @@
 #include <cbfs.h>
 #include <halt.h>
 #include <ip_checksum.h>
+#include <northbridge/intel/common/mrc_cache.h>
 #include <pc80/mc146818rtc.h>
 #include <device/pci_def.h>
 #include "raminit.h"