net: phy: marvell10g: use genphy_c45_an_config_aneg

Use new function genphy_c45_config_aneg() in mv3310_config_aneg().

v2:
- add a comment regarding 1000BaseT vendor registers
v3:
- rebased

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