net/sched: sch_cake: Factor out config variables into separate struct

net/sched: sch_cake: Factor out config variables into separate struct

Factor out all the user-configurable variables into a separate struct
and embed it into struct cake_sched_data. This is done in preparation
for sharing the configuration across multiple instances of cake in an mq
setup.

No functional change is intended with this patch.

Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://patch.msgid.link/20260109-mq-cake-sub-qdisc-v8-2-8d613fece5d8@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>