Additionally, don't assign directly to disk->queue, otherwise
blk_put_queue (called via put_disk) will choke (panic) on the errno
stored there.

Bug found by code inspection after Omar found a similar issue in
virtio_blk.  Compile-tested only.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>