ARM: kirkwood: Move to ID based MBus window creation

With the introduction of the ID based MBus API, it's better
to switch to use it instead of the current name based scheme.

This will allow to deprecate the name based API, once every
user is removed.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>