sched,ion: Convert to sched_set_normal()

In an attempt to take away sched_setscheduler() from modules, change
this into sched_set_normal(.nice = 19).

Cc: john.stultz@linaro.org
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>

drivers/staging/android/ion/ion_heap.c

@@ -244,8 +244,6 @@ static int ion_heap_deferred_free(void *data)
 
 int ion_heap_init_deferred_free(struct ion_heap *heap)
 {
-	struct sched_param param = { .sched_priority = 0 };
-
 	INIT_LIST_HEAD(&heap->free_list);
 	init_waitqueue_head(&heap->waitqueue);
 	heap->task = kthread_run(ion_heap_deferred_free, heap,
@@ -255,7 +253,7 @@ int ion_heap_init_deferred_free(struct ion_heap *heap)
 		       __func__);
 		return PTR_ERR_OR_ZERO(heap->task);
 	}
-	sched_setscheduler(heap->task, SCHED_IDLE, &param);
+	sched_set_normal(heap->task, 19);
 
 	return 0;
 }