net_sched: act: hide struct tcf_common from API

Now we can totally hide it from modules. tcf_hash_*() API's
will operate on struct tc_action, modules don't need to care about
the details.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/tc_act/tc_gact.h b/include/net/tc_act/tc_gact.h
index 9e3f676..9fc9b57 100644
--- a/include/net/tc_act/tc_gact.h
+++ b/include/net/tc_act/tc_gact.h
@@ -11,7 +11,7 @@
         int			tcfg_paction;
 #endif
 };
-#define to_gact(pc) \
-	container_of(pc, struct tcf_gact, common)
+#define to_gact(a) \
+	container_of(a->priv, struct tcf_gact, common)
 
 #endif /* __NET_TC_GACT_H */