Add VTS tests for audio effects

Added tests covering IEffect, IEqualizerEffect, and
ILoudnessEnhancer interfaces.

Minor corrections in the interface definitions and implementations:

 - fixed descriptions and @callflow annotations in IEffect;

 - fixed type used for band levels in IEqualizerEffect;

 - fixed specification of frequencies in IEqualizerEffect;

 - fixed some bugs in previously non-execrices Effects code;

 - warning messages changed to error messages.

Test: this is a test
Bug: 32022706
Change-Id: I0e0bc111b07d944ad8a0321e8b1ec703f8d1a73e
diff --git a/audio/effect/2.0/default/EqualizerEffect.h b/audio/effect/2.0/default/EqualizerEffect.h
index c9bed4f..9e8d75b 100644
--- a/audio/effect/2.0/default/EqualizerEffect.h
+++ b/audio/effect/2.0/default/EqualizerEffect.h
@@ -114,7 +114,7 @@
     // Methods from ::android::hardware::audio::effect::V2_0::IEqualizerEffect follow.
     Return<void> getNumBands(getNumBands_cb _hidl_cb)  override;
     Return<void> getLevelRange(getLevelRange_cb _hidl_cb)  override;
-    Return<Result> setBandLevel(uint16_t band, uint16_t level)  override;
+    Return<Result> setBandLevel(uint16_t band, int16_t level)  override;
     Return<void> getBandLevel(uint16_t band, getBandLevel_cb _hidl_cb)  override;
     Return<void> getBandCenterFrequency(
             uint16_t band, getBandCenterFrequency_cb _hidl_cb)  override;
@@ -132,7 +132,7 @@
     virtual ~EqualizerEffect();
 
     void propertiesFromHal(
-            t_equalizer_settings& halProperties,
+            const t_equalizer_settings& halProperties,
             IEqualizerEffect::AllProperties* properties);
     std::vector<uint8_t> propertiesToHal(
             const IEqualizerEffect::AllProperties& properties,