Revert "Remove "Volume adjust preference" on tablets"

This reverts commit 361f86698e58a887b6164b3d4c527a7e79f4f674.
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