Add return value annotation to getSoundTriggerMode

Bug: 181064773
Test: build and manually verify SoundTrigger
Change-Id: I75929c9fc0747e4df9dc385b580dff844b4a7b8c

core/java/android/os/BatterySaverPolicyConfig.java

@@ -247,6 +247,7 @@ public final class BatterySaverPolicyConfig implements Parcelable {
     /**
      * Get the SoundTrigger mode while in Battery Saver.
      */
+    @PowerManager.SoundTriggerPowerSaveMode
     public int getSoundTriggerMode() {
         return mSoundTriggerMode;
     }