qxl: fix Kconfig deps - select FB_DEFERRED_IO

Signed-off-by: NAndrew Jones <drjones@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/qxl/Kconfig

@@ -4,6 +4,7 @@ config DRM_QXL
 	select FB_SYS_FILLRECT
 	select FB_SYS_COPYAREA
 	select FB_SYS_IMAGEBLIT
+	select FB_DEFERRED_IO
         select DRM_KMS_HELPER
         select DRM_TTM
 	help