Revert "AudioOutputBase: Fix Coverity 746810. Dereference after null …

…check. False positive, and flagged as such with Coverity, but applying a 'fix' anyway to keep other SA tools quiet."

This reverts commit 3e30a16.

mythtv/libs/libmyth/audio/audiooutputbase.cpp

@@ -1226,7 +1226,7 @@ int AudioOutputBase::CopyWithUpmix(char *buffer, int frames, uint &org_waud)
     int bpf   = bytes_per_frame;
     int off   = 0;
 
-    if (!needs_upmix || !upmixer)
+    if (!needs_upmix)
     {
         int num  = len;