Upon unregistering the user interface, we mark the GPU as wedged to
ensure we push no new work to the GPU, and to flush all current work
from the GPU. Move this call to the GT backend.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200221235135.2883006-1-chris@chris-wilson.co.uk