Fix sound effect attenuation calculation

The sound effect volume attenuation calculation is wrong: the
 division by 20 was always returning 1 or 0.
In AudioService, rename the sound effect attenuation value to
 follow the naming conventions for static variables.

Change-Id: I3c36d50f4470ff09ca98cb944aefb5ad0f968782
diff --git a/media/java/android/media/AudioService.java b/media/java/android/media/AudioService.java
index 6f85bf8..d2a8298 100644
--- a/media/java/android/media/AudioService.java
+++ b/media/java/android/media/AudioService.java
@@ -382,7 +382,7 @@
     // message looper for SoundPool listener
     private Looper mSoundPoolLooper = null;
     // volume applied to sound played with playSoundEffect()
-    private static int SOUND_EFFECT_VOLUME_DB;
+    private static int sSoundEffectVolumeDb;
     // getActiveStreamType() will return STREAM_NOTIFICATION during this period after a notification
     // stopped
     private static final int NOTIFICATION_VOLUME_DELAY_MS = 5000;
@@ -439,7 +439,7 @@
             "ro.config.vc_call_vol_steps",
            MAX_STREAM_VOLUME[AudioSystem.STREAM_VOICE_CALL]);
 
-        SOUND_EFFECT_VOLUME_DB = context.getResources().getInteger(
+        sSoundEffectVolumeDb = context.getResources().getInteger(
                 com.android.internal.R.integer.config_soundEffectVolumeDb);
 
         mVolumePanel = new VolumePanel(context, this);
@@ -2882,7 +2882,7 @@
                 float volFloat;
                 // use default if volume is not specified by caller
                 if (volume < 0) {
-                    volFloat = (float)Math.pow(10, SOUND_EFFECT_VOLUME_DB/20);
+                    volFloat = (float)Math.pow(10, (float)sSoundEffectVolumeDb/20);
                 } else {
                     volFloat = (float) volume / 1000.0f;
                 }