[PATCH 2.6.23] ibmebus: Prevent bus_id collisions

[Joel Schopp]

> There are currently two GX devices, eHCA and eHEA, which both reside 
> beneath the root node - this is required by architecture for those 
> devices. Unless they invent a device called 
> "supercalifragilisticexpialidocious", devices in the root note will have a 
> full_name of less than 31 chars. Even in that case, the truncation occurs 
> at the beginning, so the @xxx part that makes the nodes unique will stay 
> in place.
> 

OK, didn't realize it had to be beneath the root node, and that the 
truncation truncated the front and not the back.  I would have done it 
differently, but this should work.

Acked-by: Joel Schopp <jschopp at austin.ibm.com>