net/mlx5: support two ports hairpin mode

net/mlx5: support two ports hairpin mode

In order to support hairpin between two ports, mlx5 PMD needs to
implement the functions and provide them as the function pointers.

The bind and unbind functions are executed per port pairs. All the
hairpin queues between the two ports should have the same attributes
during queues setup. Different configurations among queue pairs from
the same ports are not supported. It is allowed that two ports only
have one direction hairpin.

In order to set up the connection between two queues, peer Rx queue
HW information must be fetched via the internal RTE API and the queue
information could be used to modify the SQ object. Then the RQ object
will be modified with the Tx queue HW information. The reverse
operation is not supported right now.

When disconnecting the queues pair, SQ and RQ object should be reset
without any peer HW information. The unbinding operation will try to
disconnect all Tx queues from the port from the Rx queues of the peer
port.

Tx explicit mode attribute will be saved and used when creating a
hairpin flow.

Signed-off-by: Bing Zhao <bingz@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>