GBA: Add more savestate checks
GBA: Add more savestate checks

jeremyherbert/mgba,mgba-emu/mgba,fr500/mgba,askotx/mgba,AdmiralCurtiss/mgba,Anty-Lemon/mgba,iracigt/mgba,askotx/mgba,cassos/mgba,libretro/mgba,Touched/mgba,bentley/mgba,bentley/mgba,Iniquitatis/mgba,askotx/mgba,libretro/mgba,mgba-emu/mgba,sergiobenrocha2/mgba,sergiobenrocha2/mgba,fr500/mgba,sergiobenrocha2/mgba,jeremyherbert/mgba,jeremyherbert/mgba,Anty-Lemon/mgba,Anty-Lemon/mgba,libretro/mgba,AdmiralCurtiss/mgba,MerryMage/mgba,fr500/mgba,MerryMage/mgba,libretro/mgba,Anty-Lemon/mgba,Iniquitatis/mgba,cassos/mgba,zerofalcon/mgba,cassos/mgba,MerryMage/mgba,Iniquitatis/mgba,askotx/mgba,mgba-emu/mgba,Touched/mgba,iracigt/mgba,Touched/mgba,iracigt/mgba,sergiobenrocha2/mgba,libretro/mgba,matthewbauer/mgba,jeremyherbert/mgba,mgba-emu/mgba,zerofalcon/mgba,sergiobenrocha2/mgba,matthewbauer/mgba,Iniquitatis/mgba,fr500/mgba,AdmiralCurtiss/mgba,iracigt/mgba,zerofalcon/mgba