framework:Thread synchronization for UI update

Issue : Framework reboot was observed due to out of sync between
        two threads which inturn causes Null pointer exception
        while updating airplanemode.
Fix : Handled Null pointer exception and the crash is not observed.
CRs-Fixed: 570122

Change-Id: I2e969f6e7726ffcf8648b366ebb54cb2b0afc292
Remove unnecessary updateSurfaceScreenOn call.

This change stops updateSurfaceScreenOn() from being called one time
right after another. It's called at the end of stayAwake(boolean awake),
which is called right before updateSurfaceScreenOn() in release().

Change-Id: I3e5db322f0abce0cd37320a103015ba72dffa64f