GBA I/O: Fix writing to out-of-bounds 8-bit I/O registers
GBA I/O: Fix writing to out-of-bounds 8-bit I/O registers

mgba-emu/mgba,sergiobenrocha2/mgba,Anty-Lemon/mgba,Anty-Lemon/mgba,sergiobenrocha2/mgba,Iniquitatis/mgba,libretro/mgba,Anty-Lemon/mgba,iracigt/mgba,mgba-emu/mgba,iracigt/mgba,fr500/mgba,libretro/mgba,jeremyherbert/mgba,fr500/mgba,mgba-emu/mgba,jeremyherbert/mgba,sergiobenrocha2/mgba,Iniquitatis/mgba,jeremyherbert/mgba,Iniquitatis/mgba,libretro/mgba,iracigt/mgba,iracigt/mgba,jeremyherbert/mgba,fr500/mgba,sergiobenrocha2/mgba,libretro/mgba,mgba-emu/mgba,Anty-Lemon/mgba,sergiobenrocha2/mgba,libretro/mgba,fr500/mgba,Iniquitatis/mgba