s4-common: use backlight brightness node for unblank

Change-Id: Ia54e35e1730f62436573970224df3b93f9283554
s4-common: add escaping quotes

Change-Id: Ieaaf6de401a5c91c9ab8b3d614d85f1b4f47bf80
Merge remote-tracking branch 'upstream/cm-11.0' into cm-11.0