Alpha Blending Mixer and Gamma Corrector - Changes to control registers

Seems like the control registers for Alpha Blending Mixer and Gamma Corrector have been changed from 6.0sp1 to 6.1. Without carefully reading the VIP user guide, it is very possible that you would miss these subtle changes:

- Alpha Blending Mixer:

Address 1-3 is no longer being used.

- Gamma Corrector:

The gamma lookup table has been moved to 1 - 2^N