net: Use skb_frag_off accessors

Use accessor functions for skb fragment's page_offset instead
of direct references, in preparation for bvec conversion.

Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index 32c364d..4d42244 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -85,7 +85,7 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
 		if (dlen < len)
 			len = dlen;
 
-		frag->page_offset = 0;
+		skb_frag_off_set(frag, 0);
 		skb_frag_size_set(frag, len);
 		memcpy(skb_frag_address(frag), scratch, len);