block/swim3: 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.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20210927220302.1073499-2-mcgrof@kernel.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/swim3.c

@@ -1229,7 +1229,9 @@ static int swim3_attach(struct macio_dev *mdev,
 	disk->flags |= GENHD_FL_REMOVABLE;
 	sprintf(disk->disk_name, "fd%d", floppy_count);
 	set_capacity(disk, 2880);
-	add_disk(disk);
+	rc = add_disk(disk);
+	if (rc)
+		goto out_cleanup_disk;
 
 	disks[floppy_count++] = disk;
 	return 0;