configs: decrease codec gain for TTY headset mic

Decrease codec gain for TTY headset mic usecase which
was high and needed calibration to offset it. With this
change the offset can be removed.

Change-Id: Ifc68a1765ddf069676f398eed9410ba244b0a19b
diff --git a/configs/msmnile/mixer_paths_tavil.xml b/configs/msmnile/mixer_paths_tavil.xml
index b2c8be2..381264c 100644
--- a/configs/msmnile/mixer_paths_tavil.xml
+++ b/configs/msmnile/mixer_paths_tavil.xml
@@ -2709,6 +2709,7 @@
     <path name="voice-tty-full-headset-mic">
         <path name="amic2" />
         <ctl name="ADC2 Volume" value="0" />
+        <ctl name="DEC0 Volume" value="84" />
     </path>
 
     <path name="voice-tty-hco-headset-mic">