misc fixes + zaphod bugfix

[Owain G. Ainsworth]

The following patch series has a couple of misc cleanups (removal of
long dead code that at various times I have discussed removing with
various developers), but the more important fix is a fix for the use of
fbOffset and fb mappings in UMS mode that screwed up zaphod on r600+ for
several users here.

Testing in zaphod and non-zaphod mode seems to show no issues here, but
extra validation is always good.

Cheers,

-0-