net: phy: realtek: add support for EEE registers on integrated PHY's

net: phy: realtek: add support for EEE registers on integrated PHY's

EEE-related registers on newer integrated PHY's have the standard
layout, but are accessible not via MMD but via vendor-specific
registers. Emulating the standard MMD registers allows to use the
generic functions for EEE control.

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>