r8169: remove not needed checks in rtl8169_set_eee

After 9de5d235

 ("net: phy: fix aneg restart in phy_ethtool_set_eee")
we don't need the check for aneg being enabled any longer, and as
discussed with Russell configuring the EEE advertisement should be
supported even if we're in a half-duplex mode currently.

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