ethdev: add traffic management API

ethdev: add traffic management API

This patch introduces the generic ethdev API for the traffic manager
capability, which includes: hierarchical scheduling, traffic shaping,
congestion management, packet marking.

Main features:
- Exposed as ethdev plugin capability (similar to rte_flow)
- Capability query API per port, per level and per node
- Scheduling algorithms: Strict Priority (SP), Weighed Fair Queuing (WFQ)
- Traffic shaping: single/dual rate, private (per node) and shared (by
  multiple nodes) shapers
- Congestion management for hierarchy leaf nodes: algorithms of tail drop,
  head drop, WRED; private (per node) and shared (by multiple nodes) WRED
  contexts
- Packet marking: IEEE 802.1q (VLAN DEI), IETF RFC 3168 (IPv4/IPv6 ECN for
  TCP and SCTP), IETF RFC 2597 (IPv4 / IPv6 DSCP)

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Acked-by: Balasubramanian Manoharan <balasubramanian.manoharan@caviumnetworks.com>
Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>