tipc: mark expected switch fall-throughs

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

Warning level 2 was used: -Wimplicit-fallthrough=2

Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Acked-by: Ying Xue <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/tipc/bearer.c

···
 	case NETDEV_CHANGE:
 		if (netif_carrier_ok(dev))
 			break;
+		/* else: fall through */
 	case NETDEV_UP:
 		test_and_set_bit_lock(0, &b->up);
 		break;

net/tipc/link.c

···
 			skb_queue_tail(mc_inputq, skb);
 			return true;
 		}
+		/* else: fall through */
 	case CONN_MANAGER:
 		skb_queue_tail(inputq, skb);
 		return true;