Revert "workqueue: sync with hammerhead source at this commit https://github.com/franciscofranco/hammerhead/commit/27344aabf14b43ca416b77c4dd52e99700f2960d"

This reverts commit 7f2a4dab0e620d707d3464c21a2b78446e3ece73.
workqueue: backport from Linux 3.6.11
to get the following patches by Tejun Heo that improves the latency of cpu
hotplug events.
workqueue: simplify CPU hotplug code
workqueue: remove CPU offline trustee
workqueue: don't butcher idle workers on an offline CPU
workqueue: reimplement CPU online rebinding to handle idle workers
https://wiki.linaro.org/WorkingGroups/PowerManagement/Doc/Hotplug#Workqueue

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>

Conflicts:
	kernel/workqueue.c