sch_hhf: fix comparison of qlen and limit

When I use the following command, eth0 cannot send any packets.
 #tc qdisc add dev eth0 root handle 1: hhf limit 1

Because qlen need be smaller than limit, all packets were dropped.
Fix this by qlen *<=* limit.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>