pkt_sched: sch_sfq: Add dummy unbind_tcf and put handles. Was: [PATCH] sfq: add dummy bind/unbind handles

Add dummy .unbind_tcf and .put qdisc class ops for easier verification.
(All other schedulers have it like this.)
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>