EP128: VRAM / VIO access timing

[lgblgblgb]

On a real EP, accessing VRAM or VIO by the CPU is slower. Emulate this, even if it's not very accurate

[lgblgblgb]

Hook function in commit 059aa9facc694d99d89af4e5a72212f8c4e9a8df The actual code is empty though, so it doesn't make any difference currently of course :)