mb/facebook/fbg1701/fbg1701/vboot-rw.fmd: Correct FMD statement

CB:55452 uses FMAP instead of "cbfs master header".
The flash size statement in vboot-rw.fmd does not contain the start
address, resulting in a non-booting system.

Add start address to FLASH statement.

BUG = N/A
TEST = Boot Facebook FBG1701

Change-Id: Id05ad33babb416a37c657b25cdb1e98d47c1a56d
Signed-off-by: Frans Hendriks <fhendriks@eltan.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55754
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/mainboard/facebook/fbg1701/vboot-rw.fmd

@@ -1,4 +1,4 @@
-FLASH 8M {
+FLASH@0xff800000 8M {
 	SI_BIOS@0x200000 0x600000 {
 		MISC_RW@0x0 0x08000 {
 			RW_MRC_CACHE@0 0x08000