net: lan743x: Fixup EEE

The enabling/disabling of EEE in the MAC should happen as a result of
auto negotiation. So move the enable/disable into
lan743x_phy_link_status_change() which gets called by phylib when
there is a change in link status.

lan743x_ethtool_set_eee() now just programs the hardware with the LTI
timer value, and passed everything else to phylib, so it can correctly
setup the PHY.

lan743x_ethtool_get_eee() relies on phylib doing most of the work, the
MAC driver just adds the LTI timer value.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>