net: sched: cls_u32: add res to offload information

In case of egress offloads the class/flowid assigned by the filter
may be very important for offloaded Qdisc selection.  Provide this
info to drivers.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>