audio policy: add more log for preferred device selection

Add more verbose log to audio policy manager AudioTrack and
AudioRecord to debug issues related to preferred capture device
selection.

Test: make
Change-Id: I9685b4c3dfc2b84d7f89a4b33613858138e48a6f
diff --git a/media/libaudioclient/AudioTrack.cpp b/media/libaudioclient/AudioTrack.cpp
index 6765bdb..594c3f3 100644
--- a/media/libaudioclient/AudioTrack.cpp
+++ b/media/libaudioclient/AudioTrack.cpp
@@ -1555,6 +1555,8 @@
 
 status_t AudioTrack::setOutputDevice(audio_port_handle_t deviceId) {
     AutoMutex lock(mLock);
+    ALOGV("%s(%d): deviceId=%d mSelectedDeviceId=%d",
+            __func__, mPortId, deviceId, mSelectedDeviceId);
     if (mSelectedDeviceId != deviceId) {
         mSelectedDeviceId = deviceId;
         if (mStatus == NO_ERROR) {