Summary

1. Actually place the correct clocks in the PVGA-based ICS90c64a (see sources).
2. Make sure the difference between 4bpp and 8bpp in the BT484/5 ramdac is actually seen and done.
3. Forgot the ATI panning flag for the plain Mach64GX cards.
4. Fix standard VGA graphics mode for Japanese text in the Mach32 so that it's rendered correctly (if bit 5 of ati 0xb0 and bit 0 of 0x4aee clock select are 0).
5. Normalize ET4000AX clocks.
6. ET4000W32 series: fix some hwcursor issues in win3.1/winos2 (in non-24bpp modes) as well as well as the chips' clocks. Cleanup of the modes too.
7. Video7 HT208 cards: Add the 7.04 HP OEM bios and implement the clocks according to its manual (HT208, below).
8. More fixes of the stalls caused by FIFO stuff in non-FIFO modes (S3 stuff).
9. Remove unused code in vid_svga.c (vga core layer)

Checklist

• Closes #xxx
• I have tested my changes locally and validated that the functionality works as intended
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - Add Video7 VGA 1024i 7.04 HP OEM BIOS. roms#438

References

Debian TextConfig clocks
Video7 1988 datasheet