Metal Max 2 Kai (Japan) (original revision) scanline glitches

[fleroviux]

After fixing #89 the flashing text issue is now resolved, however there still are some very minor graphical issues with this game.

Incorrect white pixels in the first scanline:

The anchor in the top-left of the message box is missing white pixels at the top:

This seems to be related to when certain IO registers are latched. NanoBoyAdvance currently fetches them too early, as the renderer is scanline-based.