r8169: use phy_ethtool_(g|s)et_link_ksettings

Use phy_ethtool_(g|s)et_link_ksettings() for the respective ethtool_ops
callbacks.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>