Revert "Convert AudioFlinger mSinkBuffer to flexible format"

This reverts commit e7e676fd2866fa4898712c4effa9e624e969c182.

Bug: 13450717.
Change-Id: Ib80b0d14428fecce33c62003a1fcf83f71cee03b
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 59d5c66..3af4874 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -450,11 +450,8 @@
     virtual     String8     getParameters(const String8& keys);
     virtual     void        audioConfigChanged_l(int event, int param = 0);
                 status_t    getRenderPosition(uint32_t *halFrames, uint32_t *dspFrames);
-                // FIXME rename mixBuffer() to sinkBuffer() and remove int16_t* dependency.
-                // Consider also removing and passing an explicit mMainBuffer initialization
-                // parameter to AF::PlaybackThread::Track::Track().
-                int16_t     *mixBuffer() const {
-                    return reinterpret_cast<int16_t *>(mSinkBuffer); };
+                // TODO: rename mixBuffer() to sinkBuffer() or try to remove external use.
+                int16_t     *mixBuffer() const { return mSinkBuffer; };
 
     virtual     void detachAuxEffect_l(int effectId);
                 status_t attachAuxEffect(const sp<AudioFlinger::PlaybackThread::Track> track,
@@ -485,7 +482,7 @@
     // updated by readOutputParameters_l()
     size_t                          mNormalFrameCount;  // normal mixer and effects
 
-    void*                           mSinkBuffer;         // frame size aligned sink buffer
+    int16_t*                        mSinkBuffer;         // frame size aligned sink buffer
 
     // TODO:
     // Rearrange the buffer info into a struct/class with