mb/google/hatch/var/mushu: Add VBT

Add the missing VBT for Mushu, which is simply a copy of the one for the
hatch variant.

Change-Id: I3918ce9e7cfa6a7dafaa228a13d0f0a5b8913c66
Signed-off-by: Dominik Behr <dbehr@chromium.org>
Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60283
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Shelley Chen <shchen@google.com>

src/mainboard/google/hatch/Kconfig

@@ -118,6 +118,7 @@ config BOARD_GOOGLE_MOONBUGGY
 
 config BOARD_GOOGLE_MUSHU
 	select BOARD_GOOGLE_BASEBOARD_HATCH
+	select INTEL_GMA_HAVE_VBT
 
 config BOARD_GOOGLE_NIGHTFURY
 	select BOARD_GOOGLE_BASEBOARD_HATCH