rename AudioSystem::newAudioSessionId()

Rename AudioSystem::newAudioSessionId() to
AudioSystem::newAudioUniqueId() as it can be used
also for I/O handles.

Bug: 12378680.
Change-Id: I611ea3b5eb57a4b0774437f477ee87dc4ccc2cc2
diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index b2f46f5..bd7121e 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -2037,7 +2037,7 @@
 }
 
 
-int AudioFlinger::newAudioSessionId()
+audio_unique_id_t AudioFlinger::newAudioUniqueId()
 {
     return nextUniqueId();
 }