AudioSystem: refactor audio config cache and callbacks

Clean up implementation of audio configuration cache and
callback events from AudioFlinger:

- Define class AudioIoDescriptor for audio input and output
configurations outside of AudioSystem class.
- Do not use void * but an AudioIoDescriptor as argument to
audio config callbacks from AudioFlinger.
- Remove unused configuration events.
- Move AudioSystem audio input and output cache from static singletons to
members of AudioFlingerClient subclass.

Change-Id: I67c196c32c09ce2756af0755ee1fe631040c3270
diff --git a/include/media/IAudioFlingerClient.h b/include/media/IAudioFlingerClient.h
index 75a9971..0080bc9 100644
--- a/include/media/IAudioFlingerClient.h
+++ b/include/media/IAudioFlingerClient.h
@@ -22,6 +22,7 @@
 #include <binder/IInterface.h>
 #include <utils/KeyedVector.h>
 #include <system/audio.h>
+#include <media/AudioIoDescriptor.h>
 
 namespace android {
 
@@ -33,7 +34,8 @@
     DECLARE_META_INTERFACE(AudioFlingerClient);
 
     // Notifies a change of audio input/output configuration.
-    virtual void ioConfigChanged(int event, audio_io_handle_t ioHandle, const void *param2) = 0;
+    virtual void ioConfigChanged(audio_io_config_event event,
+                                 const sp<AudioIoDescriptor>& ioDesc) = 0;
 
 };