drm/rcar-du: make fbdev support really optional

Currently enabling R-Car DRM support automatically pulls in
fbdev dependency. However this dep is unnecessary since
DRM core already handles this for us (DRM_FBDEV_EMULATION).
Signed-off-by: NTobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: NSean Paul <seanpaul@chromium.org>

drivers/gpu/drm/rcar-du/Kconfig

@@ -6,7 +6,6 @@ config DRM_RCAR_DU
 	select DRM_KMS_HELPER
 	select DRM_KMS_CMA_HELPER
 	select DRM_GEM_CMA_HELPER
-	select DRM_KMS_FB_HELPER
 	select VIDEOMODE_HELPERS
 	help
 	  Choose this option if you have an R-Car chipset.