scsi: sd: Clean up gendisk if device_add_disk() failed

We forgot to call blk_cleanup_disk() when device_add_disk() failed.  This
would cause a memory leak of gendisk and sched_tags allocated in
elevator_init_mq()

Reference:https://syzkaller.appspot.com/x/log.txt?x=13b41dcb700000
Reported-and-tested-by: syzbot+f08c77040fa163a75a46@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20220401011018.1026553-1-haowenchao@huawei.com
Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Wenchao Hao

drivers/scsi/sd.c

@@ -3475,6 +3475,7 @@ static int sd_probe(struct device *dev)
 	error = device_add_disk(dev, gd, NULL);
 	if (error) {
 		put_device(&sdkp->disk_dev);
+		blk_cleanup_disk(gd);
 		goto out;
 	}