I never got an acknowledgement to this email:
http://www.spinics.net/lists/devicetree/msg143944.html
The "bus" number is something that is defined as part of the hardware
specification for this device.

It seems we will not be able to do away with the "bus" number parameter.

Joel suggested going back to the way I was originally doing it:
http://www.spinics.net/lists/devicetree/msg144134.html

Cheers