net/mlx5e: Add ethtool RSS configuration options

- get_rxfh_key_size
- get_rxfh_indir_size
- get/set_rxfh indirection table and RSS Toeplitz hash key
- get_rxnfc

Signed-off-by: Achiad Shochat <achiad@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>