[NET]: Annotate skb_checksum() and callers.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 64fa7f4..784129f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1334,8 +1334,8 @@
 extern void	       skb_free_datagram(struct sock *sk, struct sk_buff *skb);
 extern void	       skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
 					 unsigned int flags);
-extern unsigned int    skb_checksum(const struct sk_buff *skb, int offset,
-				    int len, unsigned int csum);
+extern __wsum	       skb_checksum(const struct sk_buff *skb, int offset,
+				    int len, __wsum csum);
 extern int	       skb_copy_bits(const struct sk_buff *skb, int offset,
 				     void *to, int len);
 extern int	       skb_store_bits(const struct sk_buff *skb, int offset,