net: phy: remove gen10g_config_init

ETHTOOL_LINK_MODE_10000baseT_Full_BIT is set anyway in the supported
and advertising bitmap because it's part of PHY_10GBIT_FEATURES.
And all users of gen10g_config_init use PHY_10GBIT_FEATURES.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>