net: bridge: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of letting the code fall
through to the next case.

Link: https://github.com/KSPP/linux/issues/115
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_input.c

@@ -144,6 +144,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 		break;
 	case BR_PKT_UNICAST:
 		dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
+		break;
 	default:
 		break;
 	}