intel_idle: Fix deallocation order on the driver exit path.

intel_idle: Fix deallocation order on the driver exit path.

Orabug: 24810432

In the module_exit() method, this driver first frees its per-CPU
pointer, then unregisters a callback making use of the pointer.
Furthermore, the function, intel_idle_cpuidle_devices_uninit, is racy
against CPU hot plugging as it calls for_each_online_cpu().

This patch corrects the issues by unregistering first on the exit path
while holding the hot plug lock.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 51319918bcc31f901646fc66348d41cf74ee0566)
Signed-off-by: Brian Maly <brian.maly@oracle.com>