Merge branch 'net-phy-improve-PM-handling-of-PHY-MDIO'

Heiner Kallweit says:

====================
net: phy: improve PM handling of PHY/MDIO

Current implementation of MDIO bus PM ops doesn't actually implement
bus-specific PM ops but just calls PM ops defined on a device level
what doesn't seem to be fully in line with the core PM model.

When looking e.g. at __device_suspend() the PM core looks for PM ops
of a device in a specific order:
1. device PM domain
2. device type
3. device class
4. device bus

I think it has good reason that there's no PM ops on device level.
The situation can be improved by modeling PHY's as device type of
a MDIO device. If for some other type of MDIO device PM ops are
needed, it could be modeled as struct device_type as well.
====================

Tested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>