audio: rename virtualizer stage to spatializer

Use audio spatializer and spatialization instead of
virtualizer stage to reflect the name chosen for public APIs.

Bug: 188502620
Test: make
Change-Id: I7974c5b159722efd795e0b0b79ddbb0658c52034
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index d3cae76..1d9f82c 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -7064,7 +7064,7 @@
 
 // ----------------------------------------------------------------------------
 
-AudioFlinger::VirtualizerStageThread::VirtualizerStageThread(const sp<AudioFlinger>& audioFlinger,
+AudioFlinger::SpatializerThread::SpatializerThread(const sp<AudioFlinger>& audioFlinger,
                                                              AudioStreamOut* output,
                                                              audio_io_handle_t id,
                                                              bool systemReady,
@@ -7073,7 +7073,7 @@
 {
 }
 
-void AudioFlinger::VirtualizerStageThread::checkOutputStageEffects()
+void AudioFlinger::SpatializerThread::checkOutputStageEffects()
 {
     bool hasVirtualizer = false;
     bool hasDownMixer = false;