Remove prvSelectHighestPriorityTask call in vTaskSuspend (#610)

Remove prvSelectHighestPriorityTask call in vTaskSuspend (#610)

* Remove prvSelectHighestPriorityTask call in vTaskSuspend

* Every core starts with an idle task in SMP implementation and
  taskTASK_IS_RUNNING only return ture when the task is idle task before
  scheduler started. So prvSelectHighestPriorityTask won't be called in
  vTaskSuspend before scheduler started.
* Update prvSelectHighestPriorityTask to ensure that this function is
  called only when scheduler started.

* Fix kernel checker error