kernel: fq_codel match flows_cnt to limit sizing

kernel: fq_codel match flows_cnt to limit sizing

OpenWRT changed the default fq_codel sch->limit from 10240 to 1024,
without also adjusting q->flows_cnt.  Eric Dumazet explains below that
you must also adjust the buckets (q->flows_cnt) for this not to break.

Eric explains: Limit of 1024 packets and 1024 flows is not wise I think.
(If all buckets are in use, each bucket has a virtual queue of 1 packet,
which is almost the same than having no queue at all)

I suggest to have at least 8 packets per bucket, to let Codel have a
chance to trigger.  So you could either reduce number of buckets to 128
(if memory is tight), or increase limit to 8192.

flows_cnt is now set to 1024/8=128

Signed-off-by: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>