net_sched: remove the leftover cleanup_a()

After refactoring tc_action into tcf_common, we no
longer need to cleanup temporary "actions" in list,
they are permanently stored in the hashtable.

Fixes: a85a970a ("net_sched: move tc_action into tcf_common")
Reported-by: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>