[PATCH 2/6] gxfb: clean up register definitions

[Andres Salomon]

Note: this is a continuation of prior gxfb patches, and also depends upon the
MSR cleanup patch.  All those patches can be found here:

http://git.infradead.org/?p=geode.git;a=summary

This one simply makes register definitions consistent w/ the data book,
saving much sanity when attempting to double-check that register handling
is correct (especially in the later power management patches).