[GameBoy] Sound samples on Wave channel needs improvement

[jkjwong]

Referring to this feature - "Anti-aliased audio synthesis with support for APU changes per sample (supports Pikachu's voice in Pokemon Yellow/Pokemon Pinball)".

On Pokemon Yellow, after you skip the intro and before the title sequence, the "Pikachu" sound sample is still very hissy.

Likewise on LSDJ, the drum kit sounds on the WAV channel are also hissy and should be cleaner as on real hardware of other emulators like Gambatte or BGB.