Fix MRC cache update delays

When no valid MRC cache area is found, the mrc_cache data structure
was used without prior initialization. This sometimes caused a long
delay when booting because compute_ip_checksum would checksum up to
4GB of memory.

Change-Id: I6a0ca1aa618838bbc3d042be425700fc34b427f2
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/1277
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
diff --git a/src/northbridge/intel/sandybridge/Kconfig b/src/northbridge/intel/sandybridge/Kconfig
index 67b3def..7dfd10d 100644
--- a/src/northbridge/intel/sandybridge/Kconfig
+++ b/src/northbridge/intel/sandybridge/Kconfig
@@ -78,6 +78,24 @@
 	int
 	default 512
 
+# FIXME: build from rom size
+config MRC_CACHE_BASE
+	hex
+	default 0xff800000
+
+config MRC_CACHE_LOCATION
+	hex
+	default 0x370000
+
+config MRC_CACHE_SIZE
+	hex
+	default 0x10000
+
+config MRC_CACHE_ALIGNMENT
+	hex
+	default 0x1000
+
+
 config DCACHE_RAM_BASE
 	hex
 	default 0xff7e0000