netfilter: only do skb_checksum_help on CHECKSUM_PARTIAL in ip_queue

While doing yet another audit on ip_summed I noticed ip_queue
calling skb_checksum_help unnecessarily.  As we will set ip_summed
to CHECKSUM_NONE when necessary in ipq_mangle_ipv4, there is no
need to zap CHECKSUM_COMPLETE in ipq_build_packet_message.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/ipv4/netfilter/ip_queue.c

@@ -160,8 +160,7 @@ ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
 		break;
 
 	case IPQ_COPY_PACKET:
-		if ((entry->skb->ip_summed == CHECKSUM_PARTIAL ||
-		     entry->skb->ip_summed == CHECKSUM_COMPLETE) &&
+		if (entry->skb->ip_summed == CHECKSUM_PARTIAL &&
 		    (*errp = skb_checksum_help(entry->skb))) {
 			read_unlock_bh(&queue_lock);
 			return NULL;