Summary

1. ATI Extended 8514/A mode may not use bit 5 of ATI reg 0xb0 sometimes but at the same time it won't use the standard VGA way of setting up 256+ colors, therefore, in the VGA DAC writes, use standard VGA way to revert to VGA mode in the writes instead of relying on bit 5 of ATI reg 0xb0 being enabled/disabled there. Fixes mode switches in VLB/PCI configurations using Windows 9x and possibly other stuff, ISA is unaffected and still works fine.
2. Added more logs and and remove/set I/O handlers correctly for the PCI side.

Checklist

• Closes #xxx
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - https://github.com/86Box/roms/pull/changeme/

References

Provide links to datasheets or other documentation that helped you implement this pull request.