ethdev: add hairpin queue

ethdev: add hairpin queue

This commit introduce hairpin queue type.

The hairpin queue in build from Rx queue binded to Tx queue.
It is used to offload traffic coming from the wire and redirect it back
to the wire.

There are 3 new functions:
- rte_eth_dev_hairpin_capability_get
- rte_eth_rx_hairpin_queue_setup
- rte_eth_tx_hairpin_queue_setup

In order to use the queue, there is a need to create rte_flow
with queue / RSS action that targets one or more of the Rx queues.

Signed-off-by: Ori Kam <orika@mellanox.com>
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>