net_sched: get rid of some forward declarations

If we move up tcf_fill_node() we can get rid of these
forward declarations.

Also, move down tfilter_notify_chain() to group them together.

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: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>