overlay: fix zero brightness scenario

NOTICE: 10 is the default value, we set it to 20
init: power: fix second core frequency

Appearently, there was an issue where the second core was shut off
while the ramdisk was still writing changes to sys devices (even cpu1).
This change forces the second core to online right before we want to
actually write values to it's sys interface.
Merge remote-tracking branch 'origin/cm-10.1' into cm-10.1-ubuntu