Merge Perforce chance 219924 to head:

Merge Perforce chance 219924 to head:

  In a sign of weakness, replicate the MIPS bus_space_generic.c to
  produce a new FDT version, which will perform necessary address
  space translation for bus_space -- the solution used in NLM's MIPS
  FDT support, but possibly not quite the right thing.  This is
  inconsistent with regular I/O via the nexus and the generic
  bus_space, which instead perform translation via pmap_mapdev()
  when a resource is activated.  However, it will work while I
  attempt to identify what the right way to reconcile possible
  approaches.

  (Another approach might be to make simplebus use Nexus's activate
  routine instead of a generic one?)

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