net/mlx5e: Report correct auto negotiation and allow toggling

Previous to this patch auto negotiation was reported off although it was
on by default in hardware. This patch reports the correct information to
ethtool and allows the user to toggle it on/off.

Added another parameter to set port proto function in order to pass
the auto negotiation field to the hardware.

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