net/mlx5e: IPoIB, Add PKEY child interface ethtool ops

Similar to VLAN interfaces child interfaces have limited ethtool
support. In current code the main limitation that does not
allow child interface ethtool configuration is due to shared
resources which are managed by the parent.
Signed-off-by: Alex Vesker <valex@mellanox.com>
Reviewed-by: Erez Shitrit <erezsh@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/ipoib/ethtool.c

@@ -250,3 +250,8 @@ const struct ethtool_ops mlx5i_ethtool_ops = {
 	.get_link_ksettings = mlx5i_get_link_ksettings,
 	.get_link           = ethtool_op_get_link,
 };
+
+const struct ethtool_ops mlx5i_pkey_ethtool_ops = {
+	.get_drvinfo        = mlx5i_get_drvinfo,
+	.get_link           = ethtool_op_get_link,
+};

drivers/net/ethernet/mellanox/mlx5/core/ipoib/ipoib.h

@@ -39,6 +39,7 @@
 #define MLX5I_MAX_NUM_TC 1
 
 extern const struct ethtool_ops mlx5i_ethtool_ops;
+extern const struct ethtool_ops mlx5i_pkey_ethtool_ops;
 
 #define MLX5_IB_GRH_BYTES       40
 #define MLX5_IPOIB_ENCAP_LEN    4

drivers/net/ethernet/mellanox/mlx5/core/ipoib/ipoib_vlan.c

@@ -279,8 +279,8 @@ static void mlx5i_pkey_init(struct mlx5_core_dev *mdev,
 	/* Override parent ndo */
 	netdev->netdev_ops = &mlx5i_pkey_netdev_ops;
 
-	/* Currently no ethtool support */
-	netdev->ethtool_ops = NULL;
+	/* Set child limited ethtool support */
+	netdev->ethtool_ops = &mlx5i_pkey_ethtool_ops;
 
 	/* Use dummy rqs */
 	priv->channels.params.log_rq_size = MLX5E_PARAMS_MINIMUM_LOG_RQ_SIZE;