[Cake] Backporting 'tc class' support

[Georgios Amanakis]

On Mon, 2018-07-16 at 12:18 +0200, Toke Høiland-Jørgensen wrote:
> Right, pushed an update to this effect. Will submit it upstream as
> well
> once someone has verified that it does what it's supposed to :)

I just verified it works as it should on diffserv3.

# tc qdisc add dev ens4 root handle 8011 cake bandwidth 18000kbit dual-
dsthost docsis ingress
# tc filter add dev ens4 parent 8011: protocol all u32 match u32 0 0
action skbedit priority 8011:1

In the second command: 
skbedit priority 8011:1 --> Bulk
skbedit priority 8011:2 --> Best Effort
skbedit priority 8011:3 --> Voice

George