Fix issue #15195464: battery history says wakelock held when it's not

Simplify full wake lock logging, so wake_lock_in is a completely
separate event from wake_lock and provides the full real raw log
of wake lock events.

Also attempt to address issue #15018750 (Incorrect wakelock reporting)
by no longer being complicated and rolling up previous state in to a
new history slice.

Bug: 15195464
Bug: 15018750
Change-Id: I32154bdfc2f07113be969f9db5503b2f2807a427