Setting EFFECT_FLAG_VOLUME_CTRL for DynamicsProcessing effect

Fixing level handling in DynamicsProcessing effect.

Bug: 79712497
Test: manual testing and sound amplifier test
Change-Id: Ie263ab570ad55e10e1ee80795357977a24a920fd
diff --git a/media/libeffects/dynamicsproc/dsp/DPFrequency.h b/media/libeffects/dynamicsproc/dsp/DPFrequency.h
index c502eb8..be8771d 100644
--- a/media/libeffects/dynamicsproc/dsp/DPFrequency.h
+++ b/media/libeffects/dynamicsproc/dsp/DPFrequency.h
@@ -43,6 +43,7 @@
 
     //Current parameters
     float inputGainDb;
+    float outputGainDb;
     struct BandParams {
         bool enabled;
         float freqCutoffHz;