[NET]: Split skb->csum

... into anonymous union of __wsum and __u32 (csum and csum_offset resp.)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 28e4cf6..1807a30 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -422,7 +422,7 @@
 		/*
 		 * Only one fragment on the socket.
 		 */
-		skb->csum = offsetof(struct udphdr, check);
+		skb->csum_offset = offsetof(struct udphdr, check);
 		uh->check = ~csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, 0);
 	} else {
 		/*