ftrace: user proper API for setting RT prios in selftest

The wakeup selftest used an internal API for setting the test task priority.
This patch fixes it to use the proper API for performing such a task.

Thanks goes to Randy Dunlap for pointing out this build failure.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

kernel/trace/trace_selftest.c

@@ -410,11 +410,11 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *
 #ifdef CONFIG_SCHED_TRACER
 static int trace_wakeup_test_thread(void *data)
 {
-	struct completion *x = data;
-
 	/* Make this a RT thread, doesn't need to be too high */
+	struct sched_param param = { .sched_priority = 5 };
+	struct completion *x = data;
 
-	rt_mutex_setprio(current, MAX_RT_PRIO - 5);
+	sched_setscheduler(current, SCHED_FIFO, &param);
 
 	/* Make it know we have a new prio */
 	complete(x);