net/mlx5: Hairpin pair core object setup

Low level code to setup hairpin pair core object, deals with:
 - create hairpin RQs/SQs
 - destroy hairpin RQs/SQs
 - modifying hairpin RQs/SQs - pairing (rst2rdy) and unpairing (rdy2rst)

Unlike conventional RQs/SQs, the memory used for the packet and descriptor
buffers is allocated by the firmware and not the driver. The driver sets
the overall data size (log).

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>