mb/google/reef: Expand the coreboot RO section

Current coreboot size is not adequate for adding new features.

Note for cros: This change is for merge to ToT only and should not be
cherry-picked into reef's firmware branch.

BUG=chromium:903833
TEST=emerge-reef coreboot

Change-Id: Ie7a25c4638c474e81fb34b57de0dfc1bf393ea67
Signed-off-by: Mathew King <mathewk@chromium.org>
Reviewed-on: https://review.coreboot.org/c/31230
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/reef/chromeos.fmd

@@ -7,9 +7,8 @@ FLASH 16M {
 			FMAP@0x0 0x800
 			RO_FRID@0x800 0x40
 			RO_FRID_PAD@0x840 0x7c0
-			COREBOOT(CBFS)@0x1000 0x17b000
-			GBB@0x17c000 0x40000
-			RO_UNUSED@0x1bc000 0x40000
+			COREBOOT(CBFS)@0x1000 0x1bb000
+			GBB@0x1bc000 0x40000
 		}
 	}
 	MISC_RW@0x400000 0x30000 {