Kconfig: Move CONFIG_VIDEO_MB

Via/VX800 was the last chip not defining it.

Change-Id: Idd03f48bed881a5846b1bb3bf29254450d6cff3b
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/19748
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/Kconfig

@@ -541,11 +541,6 @@ config CACHE_ROM_SIZE_OVERRIDE
 	hex
 	default 0x0
 
-# TODO: Can probably be removed once all chipsets have kconfig options for it.
-config VIDEO_MB
-	int
-	default 0
-
 config USE_WATCHDOG_ON_BOOT
 	bool
 	default n

src/northbridge/via/vx800/Kconfig

@@ -4,3 +4,8 @@ config NORTHBRIDGE_VIA_VX800
 	select HAVE_DEBUG_RAM_SETUP
 	select HAVE_DEBUG_SMBUS
 	select LATE_CBMEM_INIT
+
+config VIDEO_MB
+	int
+	default 0 # FIXME
+	depends on NORTHBRIDGE_VIA_VX800