Changes to gt64260 PCI arbiter enable code

Please introduce these changes into the linuxppc
sources in order that the existing generic
gt64260 setup code be usable on platforms other
than the Galileo Eval Board.

The current gt64260 setup contains incorrect
assumptions about internal arbiter setup based
solely upon the detected chip revision, when
this decision is actually platform-dependent;
such code is moved to platform-specific files.

Patch also corrects some comments.


Regards,
          Michael O'Donnell
        Mission Critical Linux