Frameworks: Fix brigthnessslider PW

overlay config_screenBrightnessDim is on jb4.2 completly
controlled over the Powermanager....no need any more for it
+ fixes weird jumping issues on some devices which added
 config_screenBrightnessDim value

cheers

Change-Id: Ia67115611489fca837070b27e8a85509e519cfda