qxl: fix Kconfig deps - select FB_DEFERRED_IO

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/qxl/Kconfig b/drivers/gpu/drm/qxl/Kconfig
index 2f1a57e..d6c1279 100644
--- a/drivers/gpu/drm/qxl/Kconfig
+++ b/drivers/gpu/drm/qxl/Kconfig
@@ -4,6 +4,7 @@
 	select FB_SYS_FILLRECT
 	select FB_SYS_COPYAREA
 	select FB_SYS_IMAGEBLIT
+	select FB_DEFERRED_IO
         select DRM_KMS_HELPER
         select DRM_TTM
 	help