r8169: Add support for restarting auto-negotiation

Implement ethtooll::nway_restart by utilizing mii_nway_restart.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169.c

@@ -2344,6 +2344,13 @@ static void rtl8169_get_strings(struct net_device *dev, u32 stringset, u8 *data)
 	}
 }
 
+static int rtl8169_nway_reset(struct net_device *dev)
+{
+	struct rtl8169_private *tp = netdev_priv(dev);
+
+	return mii_nway_restart(&tp->mii);
+}
+
 static const struct ethtool_ops rtl8169_ethtool_ops = {
 	.get_drvinfo		= rtl8169_get_drvinfo,
 	.get_regs_len		= rtl8169_get_regs_len,
@@ -2359,6 +2366,7 @@ static const struct ethtool_ops rtl8169_ethtool_ops = {
 	.get_sset_count		= rtl8169_get_sset_count,
 	.get_ethtool_stats	= rtl8169_get_ethtool_stats,
 	.get_ts_info		= ethtool_op_get_ts_info,
+	.nway_reset		= rtl8169_nway_reset,
 };
 
 static void rtl8169_get_mac_version(struct rtl8169_private *tp,