tcp: Optimise GRO port comparisons

Instead of doing two 16-bit operations for the source/destination
ports, we can do one 32-bit operation to take care both.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

@@ -2544,7 +2544,7 @@ struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 
 		th2 = tcp_hdr(p);
 
-		if ((th->source ^ th2->source) | (th->dest ^ th2->dest)) {
+		if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
 			NAPI_GRO_CB(p)->same_flow = 0;
 			continue;
 		}