net/mlx5: Vectorize the low level core hairpin object

Enhance the hairpin setup code at the core to support a set of N
(RQ,SQ) pairs. This will be later used by the caller to set RSS
spreading among the different RQs.

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