nbd: fix order of cleaning up the queue and freeing the tagset

We must release the queue before freeing the tagset.

Fixes: 4af5f2e ("nbd: use blk_mq_alloc_disk and blk_cleanup_disk")
Reported-and-tested-by: syzbot+9ca43ff47167c0ee3466@syzkaller.appspotmail.com
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210706040016.1360412-1-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Wang Qing

drivers/block/nbd.c

@@ -239,8 +239,8 @@ static void nbd_dev_remove(struct nbd_device *nbd)
 
 	if (disk) {
 		del_gendisk(disk);
-		blk_mq_free_tag_set(&nbd->tag_set);
 		blk_cleanup_disk(disk);
+		blk_mq_free_tag_set(&nbd->tag_set);
 	}
 
 	/*