For 3D buffers, virtio_gpu_gem_object_open notifies.
We can have the same behavior for dumb buffer.

v2: virtio_gpu_gem_object_open always notifies
v3: avoid boolean variable
Signed-off-by: NGurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: NChia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200401223039.2860-3-gurchetansingh@chromium.orgSigned-off-by: NGerd Hoffmann <kraxel@redhat.com>