swim: 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.

Since we have a caller to do our unwinding for the disk,
and this is already dealt with safely we can re-use our
existing error path goto label which already deals with
the cleanup.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20210927220302.1073499-11-mcgrof@kernel.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/swim.c

@@ -843,7 +843,9 @@ static int swim_floppy_init(struct swim_priv *swd)
 		swd->unit[drive].disk->events = DISK_EVENT_MEDIA_CHANGE;
 		swd->unit[drive].disk->private_data = &swd->unit[drive];
 		set_capacity(swd->unit[drive].disk, 2880);
-		add_disk(swd->unit[drive].disk);
+		err = add_disk(swd->unit[drive].disk);
+		if (err)
+			goto exit_put_disks;
 		swd->unit[drive].registered = true;
 	}