Implement audio devices and streams HAL delegating to legacy HAL

Changes made to the .hal definition:

  - introduce Effect ID returned by the IEffectsFactory that
    needs to be passed to IStream.{add|remove}Effect; otherwise
    it's impossible to retrieve the underlying HAL effect handle;

  - change "bus address" in DeviceAddress to "string" type;

  - fix signature of some methods w.r.t. returning Result;

  - remove unused "struct AudioPatch".

Bug: 30222631
Test: make
Change-Id: Icb51729ef57bb2a5b0b78609735e7481bc04f95c
diff --git a/audio/effect/2.0/default/Android.mk b/audio/effect/2.0/default/Android.mk
index 13106f3..50c4bd6 100644
--- a/audio/effect/2.0/default/Android.mk
+++ b/audio/effect/2.0/default/Android.mk
@@ -26,6 +26,7 @@
     libeffects \
     liblog \
     android.hardware.audio.common@2.0 \
+    android.hardware.audio.common@2.0-util \
     android.hardware.audio.effect@2.0 \
 
 include $(BUILD_SHARED_LIBRARY)