ACPI / thermal: fix workqueue destroy order

When the thermal module is to be removed, we should destroy the wq
acpi_thermal_pm_queue after the ACPI driver's remove callback is
executed as we will need to flush the workqueue there, or a NULL pointer
access will be hit.

Reported-and-tested-by: Kui Zhang <kuizhang@gmail.com>
References: http://www.spinics.net/lists/kernel/msg1747251.html
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'acpi-thermal' into bleeding-edge

* acpi-thermal:
  ACPI / thermal: fix workqueue destroy order