drm/virtio: unlock object array on errors

We don't propagate erros to the callers.  We have to unlock object
arrays on errors.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200205181955.202485-6-olvaffe@gmail.com


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