Genesis core not switching to 448-480i

[Lisko]

Hi, not sure if this was working before but yesterday I tried the 240p test suite and it wasn't switching to 480i. Tested on pal and ntsc connected via hdmi @ 1080p with all possible vsync_adjust values and using integer scaling. Not tested via analog out but should be the same as it's the core that doesn't seems to switch resolution. I tested on the snes core and there works fine.