scsi: qla4xxx: ql4_os: mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases where
we are expecting to fall through.

Notice that, in this particular case, I replaced "allow fall-through" with
a "fall through" annotation, which is what GCC is expecting to find.

Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Acked-by: Nilesh Javali <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/qla4xxx/ql4_os.c

···
 						chap_tbl.secret_len);
 			}
 		}
-		/* allow fall-through */
+		/* fall through */
 	default:
 		return iscsi_session_get_param(cls_sess, param, buf);
 	}