Revert "Revert "audiopolicy: moves Stream Volume Curves to Engine""

This reverts commit efdbe3bfeff7c150d99900fddca005d48048f188.

Test: make
diff --git a/services/audiopolicy/engineconfigurable/src/Engine.cpp b/services/audiopolicy/engineconfigurable/src/Engine.cpp
index 719ef01..89a1694 100644
--- a/services/audiopolicy/engineconfigurable/src/Engine.cpp
+++ b/services/audiopolicy/engineconfigurable/src/Engine.cpp
@@ -113,7 +113,7 @@
                                        const audio_stream_type_t &profile)
 {
     if (setPropertyForKey<audio_stream_type_t, audio_stream_type_t>(stream, profile)) {
-        getApmObserver()->getVolumeCurves().switchVolumeCurve(profile, stream);
+        switchVolumeCurve(profile, stream);
         return true;
     }
     return false;