[SK_BUFF]: Introduce skb_network_header()

For the places where we need a pointer to the network header, it is still legal
to touch skb->nh.raw directly if just adding to, subtracting from or setting it
to another layer header.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c
index 3d6a2fc..20813ee 100644
--- a/net/sched/act_pedit.c
+++ b/net/sched/act_pedit.c
@@ -136,7 +136,7 @@
 		}
 	}
 
-	pptr = skb->nh.raw;
+	pptr = skb_network_header(skb);
 
 	spin_lock(&p->tcf_lock);