net: phy: replace genphy_10g_driver with genphy_c45_driver

Recently a number of generic functions for Clause 45 PHY's has been
added. So let's replace the old very limited genphy_10g_driver with a
genphy_c45_driver. This driver isn't limited to 10G, however it's worth
to be noted that Clause 45 doesn't cover 1000Base-T. For using
1000Base-T with a Clause 45 PHY a dedicated PHY driver using vendor
registers is needed.

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