audio: change safe volume level to 6 for CE specifications

SPL at volume level 7 is 30mV. But the CE specifications
is warring popup message must be shown more than 30mV.
So we need change safe volume level to 6.

Change-Id: I15265290e2c7a46177bdf1d8f255d29e7b10fad7
diff --git a/overlay/frameworks/base/core/res/res/values/config.xml b/overlay/frameworks/base/core/res/res/values/config.xml
index 2a4f0a5..59ccddf 100644
--- a/overlay/frameworks/base/core/res/res/values/config.xml
+++ b/overlay/frameworks/base/core/res/res/values/config.xml
@@ -129,7 +129,7 @@
     <integer name="config_defaultNotificationLedOff">9000</integer>
 
     <!-- reference volume index for music stream to limit headphone volume and display warning -->
-    <integer name="config_safe_media_volume_index">7</integer>
+    <integer name="config_safe_media_volume_index">6</integer>
 
     <!-- List of regexpressions describing the interface (if any) that represent tetherable
          USB interfaces.  If the device doesn't want to support tething over USB this should