Fix leaking CONFIG_VGA=y

Items under DEVICE_SPECIFIC_OPTIONS got selected without
the driver being selected.

Change-Id: I1797fa6175620a9291873559a6308eaea85a090e
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/14823
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/northbridge/intel/sandybridge/Kconfig

@@ -55,6 +55,7 @@ config CACHE_MRC_SIZE_KB
 
 config SANDYBRIDGE_IVYBRIDGE_LVDS
 	def_bool n
+	select VGA
 	select MAINBOARD_HAS_NATIVE_VGA_INIT
 	select MAINBOARD_HAS_NATIVE_VGA_INIT_TEXTMODECFG