Revert "termanager: disable backlight"

This reverts commit cfa58d2b8cb637b483eda372eacdfde175e469b5.

Change-Id: Id583226364a87ee27eb3b312dd4e023ed75c601c
thermanager: Correct backlight values

Change-Id: I907a0c90efb67c63f442acde5ad480e0eec47700