blk-mq: release mq's kobjects in blk_release_queue()

The kobject memory inside blk-mq hctx/ctx shouldn't have been freed
before the kobject is released because driver core can access it freely
before its release.

We can't do that in all ctx/hctx/mq_kobj's release handler because
it can be run before blk_cleanup_queue().

Given mq_kobj shouldn't have been introduced, this patch simply moves
mq's release into blk_release_queue().

Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-sysfs.c

@@ -517,6 +517,8 @@ static void blk_release_queue(struct kobject *kobj)
 
 	if (!q->mq_ops)
 		blk_free_flush_queue(q->fq);
+	else
+		blk_mq_release(q);
 
 	blk_trace_shutdown(q);