scsi_debug: fix missing "break;" in SDEBUG_UA_CAPACITY_CHANGED case

This eliminates a superfluous log message when the capacity is changed:

  "check_readiness: unexpected unit attention code=3"
Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/scsi_debug.c

@@ -816,6 +816,7 @@ static int check_readiness(struct scsi_cmnd *SCpnt, int uas_only,
 					UA_CHANGED_ASC, CAPACITY_CHANGED_ASCQ);
 			if (debug)
 				cp = "capacity data changed";
+			break;
 		default:
 			pr_warn("%s: unexpected unit attention code=%d\n",
 				__func__, k);