net_sched: cls_flow: remove faulty use of list_for_each_entry_rcu

rcu variant is not correct here. The code is called by updater (rtnl
lock is held), not by reader (no rcu_read_lock is held).

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