drm/virtio: add case for shmem objects in virtio_gpu_cleanup_object(..)

This function can be reused for hostmem objects.

v2: move virtio_gpu_is_shmem() check to virtio_gpu_cleanup_object()
v3: use-after free fix

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20200305013212.130640-2-gurchetansingh@chromium.org


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>