net/mlx5_core: Support physical port counters

Added physical port counters in the following standard formats to
ethtool statistics:
  - IEEE 802.3
  - RFC2863
  - RFC2819

Signed-off-by: Gal Pressman <galp@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>