drm: replace DRIVER_PREFER_XBGR_30BPP driver flag with mode_config quirk

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20180905060445.15008-2-kraxel@redhat.com
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index a0b202e..5d29f4b 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -809,6 +809,7 @@ struct drm_mode_config {
 
 	/* dumb ioctl parameters */
 	uint32_t preferred_depth, prefer_shadow;
+	bool quirk_addfb_prefer_xbgr_30bpp;
 
 	/**
 	 * @async_page_flip: Does this device support async flips on the primary