removed useless check for button backlight value

Change-Id: I4013061f7c2d7c2955076c8a5d9bb6ace0b081bc
Ported: Volume adjust sound preference 1/2

Author:    StevenHarperUK <StevenHarperUK@gmail.com>

Feature : Volume adjust sound preference 1/2

Adjusting the volume makes a nice "boing" sound
Personally I find this annoying
This patch makes this a preference in
Settings | Sound
    Volume adjust sound
        Play sound when adjusting volume with hard keys

The Checkbox is defaulted to ON (1 in defaults.xml)

Look for 2/2 for the Settings, Sound Panel Change

Change-Id: Iad89a0c49288094e21824aa9c9e1bf98c29cfec3