- Disable acceleration with 24bpp due to apparent broken acceleration.
    Accel at 24bpp was the cause of the crashes when people tried to use
    any depth over 16. XFree86 doesn't support 24 either.
- Disable at < 8bpp, too.
- Add the other Rage 128 PCI IDs.
- Remove unnecessary setting of scissor registers (only default scissor
    gets used).