GB Serialize: Fix audio channel 2 and 3 loading
GB Serialize: Fix audio channel 2 and 3 loading

Iniquitatis/mgba,mgba-emu/mgba,Iniquitatis/mgba,libretro/mgba,Iniquitatis/mgba,mgba-emu/mgba,Iniquitatis/mgba,mgba-emu/mgba,libretro/mgba,libretro/mgba,libretro/mgba,mgba-emu/mgba,libretro/mgba