sched/tune: report when SchedTune has not been initialized

Change-Id: Iba4e5e3d220451f04272d555e6b8e0af83a7f09d
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Srinath Sridharan <srinathsr@google.com>

kernel/sched/tune.c

@@ -939,6 +939,7 @@ schedtune_init(void)
 	return 0;
 
 nodata:
+	pr_warning("schedtune: disabled!\n");
 	rcu_read_unlock();
 	return -EINVAL;
 }