Settings: Restart existing volumizers in volume prefs.

Use the new .start() method to ensure the underlying volumizer
is always started, regardless of pref activity lifecycle.

Depends on frameworks/base:
  I2f860864161f818d5a62a28331ef1c47051fb39f

Bug:17898190
Change-Id: I55dea590c13363730549aa29f194337efccdeaf7

src/com/android/settings/notification/VolumeSeekBarPreference.java

@@ -105,6 +105,7 @@ public class VolumeSeekBarPreference extends SeekBarPreference
                 }
             };
         }
+        mVolumizer.start();
         mVolumizer.setSeekBar(mSeekBar);
         mIconView = (ImageView) view.findViewById(com.android.internal.R.id.icon);
         mCallback.onStreamValueChanged(mStream, mSeekBar.getProgress());