[APU] Refactor audio system to work with different frequencies/channel layouts

src/xenia/apu/nop/nop_audio_system.cc

@@ -30,6 +30,12 @@ X_STATUS NopAudioSystem::CreateDriver(size_t index,
   return X_STATUS_NOT_IMPLEMENTED;
 }
 
+AudioDriver* NopAudioSystem::CreateDriver(xe::threading::Semaphore* semaphore,
+                                          uint32_t frequency, uint32_t channels,
+                                          bool need_format_conversion) {
+  return nullptr;
+}
+
 void NopAudioSystem::DestroyDriver(AudioDriver* driver) { assert_always(); }
 
 }  // namespace nop

src/xenia/apu/nop/nop_audio_system.h

@@ -27,6 +27,9 @@ class NopAudioSystem : public AudioSystem {
 
   X_STATUS CreateDriver(size_t index, xe::threading::Semaphore* semaphore,
                         AudioDriver** out_driver) override;
+  AudioDriver* CreateDriver(xe::threading::Semaphore* semaphore,
+                            uint32_t frequency, uint32_t channels,
+                            bool need_format_conversion) override;
   void DestroyDriver(AudioDriver* driver) override;
 };