mb/google/guybrush: Add default FMD file to the build

BUG=b:175143925
TEST=builds; binary has correct layout

Signed-off-by: Mathew King <mathewk@chromium.org>
Change-Id: I4f3826c8ed0dfd7219eaa5f0cc285f1fe89a4e1d
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49491
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>

src/mainboard/google/guybrush/Kconfig

@@ -9,6 +9,10 @@ config BOARD_SPECIFIC_OPTIONS
 	def_bool y
 	select SOC_AMD_CEZANNE
 
+config FMDFILE
+	string
+	default "src/mainboard/\$(CONFIG_MAINBOARD_DIR)/chromeos.fmd"
+
 config MAINBOARD_DIR
 	string
 	default "google/guybrush"