cls_matchall: fix tcf_unbind_filter missing

Fix tcf_unbind_filter missing in cls_matchall as this will trigger
WARN_ON() in cbq_destroy_class().

Fixes: fd62d9f5 ("net/sched: matchall: Fix configuration race")
Reported-by: Li Shuang <shuali@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>