drm: virtio-gpu: ensure plane is flushed to host on atomic update

This fixes drawing updates when updating planes with atomic API.

Signed-off-by: Rob Herring <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/virtio/virtgpu_plane.c

···
 				   plane->state->crtc_h,
 				   plane->state->crtc_x,
 				   plane->state->crtc_y);
+	virtio_gpu_cmd_resource_flush(vgdev, handle,
+				      plane->state->crtc_x,
+				      plane->state->crtc_y,
+				      plane->state->crtc_w,
+				      plane->state->crtc_h);
 }