net: core: 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/115Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -5265,6 +5265,7 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
 			goto another_round;
 		case RX_HANDLER_EXACT:
 			deliver_exact = true;
+			break;
 		case RX_HANDLER_PASS:
 			break;
 		default: