Merge branch 'of-mdio-Fall-back-to-mdiobus_register-with-NULL-device_node'

Florian Fainelli says:

====================
of: mdio: Fall back to mdiobus_register() with NULL device_node

This patch series updates of_mdiobus_register() such that when the device_node
argument is NULL, it calls mdiobus_register() directly. This is consistent with
the behavior of of_mdiobus_register() when CONFIG_OF=n.

I only converted the most obvious drivers, there are others that have a much
less obvious behavior and specifically attempt to deal with CONFIG_ACPI.

Changes in v2:

- fixed build error in davincin_mdio.c (Grygorii)
- reworked first patch a bit: commit message, subject and removed useless
  code comment
====================

Signed-off-by: David S. Miller <davem@davemloft.net>