net/mlx4_en: Add physical RX/TX bytes/packets counters

Add physical RX/TX packets/bytes counters into ethtool output to monitor
all traffic that was received and transmitted on the port. These
counters are available only for none Virtual Function.

Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>