drm/msm: add missing DRIVER_ATOMIC flag

Somehow this got lost when msm atomic support was first merged.

Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/msm_drv.c

@@ -885,6 +885,7 @@ static struct drm_driver msm_driver = {
 				DRIVER_GEM |
 				DRIVER_PRIME |
 				DRIVER_RENDER |
+				DRIVER_ATOMIC |
 				DRIVER_MODESET,
 	.load               = msm_load,
 	.unload             = msm_unload,