sched: make rt_sched_class, idle_sched_class static

The C files are included directly in sched.c, so they are
effectively static.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index 2bcafa37..3a4f92d 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -99,7 +99,7 @@
 /*
  * Simple, special scheduling class for the per-CPU idle tasks:
  */
-const struct sched_class idle_sched_class = {
+static const struct sched_class idle_sched_class = {
 	/* .next is NULL */
 	/* no enqueue/yield_task for idle tasks */