spufs platform dependent code

[Benjamin Herrenschmidt]

> I found you have some stuff in there specific to your platform.It assumes there is a certain south bridge, and that spuinterrupts are serviced by that south bridge.  It also makesassumptions of how the spu's are represented in the device tree.
> I've got a first cut patch to break those things out.  I'll postit soon for comment.

The device-tree representation should be made independant. We need you
guys to agree on it and stick to one representation. I strongly suggest
you document it too.

Ben.