net: phy: marvell10g: check for newly set aneg

Even if the advertisement registers content didn't change, we may have
just switched to aneg, and therefore have to trigger an aneg restart.
This matches the behavior of genphy_config_aneg().

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