mb/amd/birman/board.fmd: Move MRC cache

The EFS must be located at the 128K offset. The combination of EC,
MRC_CACHE, and FMAP push the start of the coreboot CBFS region to 128K,
leaving no room for the CBFS headers for the EFS.

Move the MRC_CACHE region to the end of the image. This matches the
chromeos MRC_CACHE layout.

Signed-off-by: Fred Reitberger <reitbergerfred@gmail.com>
Change-Id: I15e29443d2735342a5a43339f5bb095e5115349c
Reviewed-on: https://review.coreboot.org/c/coreboot/+/72902
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/mainboard/amd/birman/board.fmd

@@ -1,8 +1,8 @@
 FLASH@0xFF000000 16M {
 	BIOS {
 		EC 4K
-		RW_MRC_CACHE 120K
 		FMAP 4K
 		COREBOOT(CBFS)
+		RW_MRC_CACHE 120K
 	}
 }