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_gact.c b/net/sched/act_gact.c
index 2b4ab4b..b77f5a0 100644
--- a/net/sched/act_gact.c
+++ b/net/sched/act_gact.c
@@ -125,7 +125,8 @@
 	return 0;
 }
 
-static int tcf_gact(struct sk_buff *skb, struct tc_action *a, struct tcf_result *res)
+static int tcf_gact(struct sk_buff *skb, const struct tc_action *a,
+		    struct tcf_result *res)
 {
 	struct tcf_gact *gact = a->priv;
 	int action = TC_ACT_SHOT;