cpu: move hotplugger to cpu, convert cpu settings to preferences

Change-Id: I128206cac8ebe668cbd0a9019e6fba8a55ca85a8
cleanups

Change-Id: Ic724e1c5cbff06ba18eeb1284bd46bc7460e96a3
bump versioncode and fix possible NPE

Change-Id: I7405593d8340633fe5948f4bc0b6aeee006829ad