sandybridge: Allow skipping mrc.cache

On X230 MRC fails if cache is passed to it. Until better solution is found
do not create mrc.cache

Change-Id: I7e70ebe3c4879e7ab33a9c95a0c9e40408ff5ca4
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/4680
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/northbridge/intel/sandybridge/Kconfig

@@ -70,6 +70,10 @@ config HAVE_MRC
 
 	  Note: Without this binary coreboot will not work
 
+config HAVE_MRC_CACHE
+       bool
+       default HAVE_MRC
+
 config MRC_FILE
 	string "Intel System Agent path and filename"
 	depends on HAVE_MRC

src/northbridge/intel/sandybridge/Makefile.inc

@@ -43,7 +43,7 @@ $(obj)/mrc.cache:
 	bs=$(shell printf "%d" $(CONFIG_MRC_CACHE_SIZE) ) | \
 	tr '\000' '\377' > $@
 
-cbfs-files-$(CONFIG_HAVE_MRC) += mrc.cache
+cbfs-files-$(CONFIG_HAVE_MRC_CACHE) += mrc.cache
 mrc.cache-file := $(obj)/mrc.cache
 mrc.cache-position := 0xfff80000
 mrc.cache-type := 0xac