ramips: ethernet: remove unused SIOCETHTOOL ioctl handling

This ioctl is currently routed through generic interface code.

  dev_ioctl
    dev_ethtool
      __ethtool_get_link_ksettings
        phy_ethtool_ioctl

Cc: Felix Fietkau <nbd@nbd.name>
Cc: John Crispin <john@phrozen.org>
Signed-off-by: Petr Štetiar <ynezz@true.cz>

target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -1411,19 +1411,8 @@ static int fe_do_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 	if (!priv->phy_dev)
 		return -ENODEV;
 
-	switch (cmd) {
-	case SIOCETHTOOL:
-		return phy_ethtool_ioctl(priv->phy_dev,
-				(void *) ifr->ifr_data);
-	case SIOCGMIIPHY:
-	case SIOCGMIIREG:
-	case SIOCSMIIREG:
-		return phy_mii_ioctl(priv->phy_dev, ifr, cmd);
-	default:
-		break;
-	}
 
-	return -EOPNOTSUPP;
+	return phy_mii_ioctl(priv->phy_dev, ifr, cmd);
 }
 
 static int fe_change_mtu(struct net_device *dev, int new_mtu)