Revert "power/wakelock: use single threaded workqueueus"

Avoid the concurrency management that could delay execution if there's
lots of workqueue traffic (and allow the runqueue to run on any CPU).

commit: https://github.com/Pafcholini/Nadia-kernel-kk_N7100XXUFND3/commit/3e070f7728a27a5210a24e38df124bfdc4213b13

This change made SO Android very high.