fmod: fix FmodAudioSound::get_speaker_mix()

panda/src/audiotraits/fmodAudioSound.cxx

@@ -651,7 +651,7 @@ get_3d_max_distance() const {
  * a balance [pan] function what is the point?
  */
 PN_stdfloat FmodAudioSound::
-get_speaker_mix(AudioManager::SpeakerId speaker) {
+get_speaker_mix(int speaker) {
   ReMutexHolder holder(FmodAudioManager::_lock);
   if (_channel == 0) {
     return 0.0;

panda/src/audiotraits/fmodAudioSound.h

@@ -126,7 +126,7 @@ public:
 
   AudioSound::SoundStatus status() const;
 
-  virtual PN_stdfloat get_speaker_mix(AudioManager::SpeakerId speaker);
+  virtual PN_stdfloat get_speaker_mix(int speaker);
   virtual void set_speaker_mix(PN_stdfloat frontleft, PN_stdfloat frontright, PN_stdfloat center, PN_stdfloat sub, PN_stdfloat backleft, PN_stdfloat backright, PN_stdfloat sideleft, PN_stdfloat  sideright);
 
   void set_active(bool active=true);