net/mlx5_core: Introduce offload arithmetic hardware capabilities

Define the necessary hardware structures for the offload
arithmetic capabilities and read/cache them on driver load.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>