Make returned audio interface frequency configurable

[klorfmorf]

Right now the default is to just set it as the frequency which was given in the function parameter.
On hardware the set value is different from what is actually given in the parameter.
This can cause issues in games, like in Mystical Ninja Starring Goemon, where long voice samples are layed over sequenced tracks causing desyncs in the audio.

N64ModernRuntime/librecomp/src/ai.cpp

Line 14 in a7b9470

ctx->r2 = freq;