sched,drm/scheduler: Convert to sched_set_fifo*()

Because SCHED_FIFO is a broken scheduler model (see previous patches)
take away the priority field, the kernel can't possibly make an
informed decision.

In this case, use fifo_low, because it only cares about being above
SCHED_NORMAL. Effectively no change in behaviour.

Cc: [e-mail]
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Reviewed-by: Ingo Molnar <[e-mail]>

drivers/gpu/drm/scheduler/sched_main.c

···
  */
 static int drm_sched_main(void *param)
 {
-	struct sched_param sparam = {.sched_priority = 1};
 	struct drm_gpu_scheduler *sched = (struct drm_gpu_scheduler *)param;
 	int r;
 
-	sched_setscheduler(current, SCHED_FIFO, &sparam);
+	sched_set_fifo_low(current);
 
 	while (!kthread_should_stop()) {
 		struct drm_sched_entity *entity = NULL;