cpu/hotplug: Create hotplug threads

cpu/hotplug: Create hotplug threads

In order to let the hotplugged cpu take care of the setup/teardown, we need a
seperate hotplug thread.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: Rik van Riel <[email protected]>
Cc: Rafael Wysocki <[email protected]>
Cc: "Srivatsa S. Bhat" <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Sebastian Siewior <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Paul McKenney <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul Turner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>