net_sched: improve and refactor tcf_action_put_many()

tcf_action_put_many() is mostly called to clean up actions on
failure path, but tcf_action_put_many(&actions[acts_deleted]) is
used in the ugliest way: it passes a slice of the array and
uses an additional NULL at the end to avoid out-of-bound
access.

acts_deleted is completely unnecessary since we can teach
tcf_action_put_many() scan the whole array and checks against
NULL pointer. Which also means tcf_action_delete() should
set deleted action pointers to NULL to avoid double free.

Fixes: 90b73b77 ("net: sched: change action API to use array of pointers to actions")
Cc: Jiri Pirko <jiri@mellanox.com>
Cc: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>