post_proc: add support for virtualizer capability query

Add extra virtualizer interfaces to keep align with aosp design.
Extended capabilities include:
- Stub interface to allow querying speaker angles.
- Force set output device as specific virtualize mode.
- Query virtualize mode

Stub function remains to be refined in sync with upcoming aosp
changes.

Change-Id: I3316f6d944db1c9954eda7643a5ce433defa1a6c
CRs-Fixed: 810294
diff --git a/post_proc/virtualizer.h b/post_proc/virtualizer.h
index 440c8a2..b5293fb 100644
--- a/post_proc/virtualizer.h
+++ b/post_proc/virtualizer.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2014, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2013-2015, The Linux Foundation. All rights reserved.
  * Not a Contribution.
  *
  * Copyright (C) 2013 The Android Open Source Project
@@ -33,7 +33,8 @@
     struct mixer_ctl *ctl;
     int hw_acc_fd;
     bool temp_disabled;
-    uint32_t device;
+    audio_devices_t forced_device;
+    audio_devices_t device;
     struct virtualizer_params offload_virt;
 } virtualizer_context_t;