net,act_police,rcu: remove rcu_barrier()

There is no callback of this module maybe queued
since we use kfree_rcu(), we can safely remove the rcu_barrier().
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

net/sched/act_police.c

@@ -396,7 +396,6 @@ static void __exit
 police_cleanup_module(void)
 {
 	tcf_unregister_action(&act_police_ops);
-	rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */
 }
 
 module_init(police_init_module);