net: usb: lan78xx: Utilize phy_ethtool_nway_reset

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Woojung Huh <woojung.huh@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>