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 <gustavo@embeddedor.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 2dfb492..fd6d8f1 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -610,6 +610,7 @@ static int tipc_l2_device_event(struct notifier_block *nb, unsigned long evt,
 	case NETDEV_CHANGE:
 		if (netif_carrier_ok(dev))
 			break;
+		/* else: fall through */
 	case NETDEV_UP:
 		test_and_set_bit_lock(0, &b->up);
 		break;