igc: set TP bit in 'supported' and 'advertising' fields of ethtool_link_ksettings

set TP bit in the 'supported' and 'advertising' fields. i225/226 parts
only support twisted pair copper.

Fixes: 8c5ad0da ("igc: Add ethtool support")
Signed-off-by: Prasad Koya <prasad@arista.com>
Acked-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc_ethtool.c

@@ -1708,6 +1708,8 @@ static int igc_ethtool_get_link_ksettings(struct net_device *netdev,
 	/* twisted pair */
 	cmd->base.port = PORT_TP;
 	cmd->base.phy_address = hw->phy.addr;
+	ethtool_link_ksettings_add_link_mode(cmd, supported, TP);
+	ethtool_link_ksettings_add_link_mode(cmd, advertising, TP);
 
 	/* advertising link modes */
 	if (hw->phy.autoneg_advertised & ADVERTISE_10_HALF)