net: sched: constify tcf_proto and tc_action

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index 762b027..001d1b3 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -102,7 +102,7 @@
 	return tcf_hash_release(&p->common, bind, &nat_hash_info);
 }
 
-static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
+static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
 		   struct tcf_result *res)
 {
 	struct tcf_nat *p = a->priv;