ovs-tc: allow offloading TC rules to egress qdiscs

ovs-tc: allow offloading TC rules to egress qdiscs

Offloading rules to a TC datapath only allows the creating of ingress hook
qdiscs and the application of filters to these. However, there may be
certain situations where an egress qdisc is more applicable (e.g. when
offloading to TC rules applied to OvS internal ports).

Extend the TC API in OvS to allow the creation of egress qdiscs and to add
or interact with flower filters applied to these.

Signed-off-by: John Hurley <john.hurley@netronome.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>