Hide "Volume adjustment sound" option on non-voice capable devices

On non-voice capable devices, there's no sound when adjusting the
notification volume. Remove the obsolete option from Settings.

Change-Id: I3fc9ef737eb55d591a4ecc7d79ee60b9151395b5
Merge "Hide "Volume adjustment sound" option on non-voice capable devices" into cm-11.0
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0