pktcdvd: add error handling support for add_disk()

We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling.

The out_mem2 error label already does what we need so
re-use that.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/pktcdvd.c

@@ -2728,7 +2728,9 @@ static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev)
 	/* inherit events of the host device */
 	disk->events = pd->bdev->bd_disk->events;
 
-	add_disk(disk);
+	ret = add_disk(disk);
+	if (ret)
+		goto out_mem2;
 
 	pkt_sysfs_dev_new(pd);
 	pkt_debugfs_dev_new(pd);