In preparation for a subsequent change, move the initialization of the
poll_queue delayed work from thermal_zone_device_register_with_trips()
to thermal_zone_device_init() which is called by the former.

However, because thermal_zone_device_init() is also called by
thermal_pm_notify(), make the latter call cancel_delayed_work() on
poll_queue before invoking the former, so as to allow the work
item to be re-initialized safely.

Also move thermal_zone_device_check() which needs to be defined
before thermal_zone_device_init(), so the latter can pass it to the
INIT_DELAYED_WORK() macro.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>