Fix derp in commit 5ca957ae585bbb79f9dbbf0d0d668dd9cbbc176d

Change-Id: I87cf54eaa7bd0ffb081121a49f3fbf99f61862e5
keyboard: re-add code to detect lid state

This was lost in the cm-11 merge. Without this, a change in lid state
isn't generated to light up the keyboard backlight

Change-Id: Ief35cebcb62da13afe1ae7531d69ab58e196be9e