freezer: Fix typo in freezable_schedule_timeout() comment

Signed-off-by: Himanshu Jha <himanshujha199640@gmail.com>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>