net/mlx5e: Add ethtool support for interface identify (LED blinking)

Add the needed hardware command and mlx5_ifc structs for managing LED
control.
Add set_phys_id ethtool callback to support ethtool -p flag.

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