virtio-gpu: use no-merge for fill-modes

Avoid the sticky preferred mode bit by using the no-merge version of the
function (this allows gnome-shell to resize to lower resolutions than
the default resolution)
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/virtio/virtgpu_display.c

@@ -412,7 +412,7 @@ static const struct drm_connector_funcs virtio_gpu_connector_funcs = {
 	.save = virtio_gpu_conn_save,
 	.restore = virtio_gpu_conn_restore,
 	.detect = virtio_gpu_conn_detect,
-	.fill_modes = drm_helper_probe_single_connector_modes,
+	.fill_modes = drm_helper_probe_single_connector_modes_nomerge,
 	.destroy = virtio_gpu_conn_destroy,
 	.reset = drm_atomic_helper_connector_reset,
 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,