net/mlx5e: IPoIB, Add ethtool support to get child time stamping parameters

Add support to get time stamping capabilities using ethtool for
child interface.
Usage example:
	ethtool -T CHILD-DEVNAME

This change reuses the functionality of parent devices and does not
introduce any new logic.
Signed-off-by: NFeras Daoud <ferasda@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

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

@@ -254,4 +254,5 @@ const struct ethtool_ops mlx5i_ethtool_ops = {
 const struct ethtool_ops mlx5i_pkey_ethtool_ops = {
 	.get_drvinfo        = mlx5i_get_drvinfo,
 	.get_link           = ethtool_op_get_link,
+	.get_ts_info        = mlx5i_get_ts_info,
 };