net/mlx5: Query and cache PCAM, MCAM registers on initialization

On load_one, we now cache our capabilities registers internally, similar
to QUERY_HCA_CAP. Capabilities can later be queried using macros
introduced in this patch.

Signed-off-by: Gal Pressman <galp@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>