Add LockClock to Settings menu

Change-Id: Ie9d10e7c8186354f01e29e1aaeb23b580ebd04aa
Forward port "Display options: allow configuration of wake on plug behavior"

From http://review.cyanogenmod.org/#/c/47159/

Change-Id: I601b3ccf35198d5cbda9971c693637f254b8db5d