VGM: Minor fixes - removed unnecessary "psg_dual" check - making mute mask apply to both chips when dual-chip is run
VGM: Minor fixes
- removed unnecessary "psg_dual" check
- making mute mask apply to both chips when dual-chip is run

ShiftMediaProject/game-music-emu,ShiftMediaProject/game-music-emu,ShiftMediaProject/game-music-emu