sched: mark scheduling classes as const

mark scheduling classes as const. The speeds up the code
a bit and shrinks it:

   text    data     bss     dec     hex filename
  40027    4018     292   44337    ad31 sched.o.before
  40190    3842     292   44324    ad24 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index de13a6f..32fd976 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -76,8 +76,6 @@
  */
 const_debug unsigned int sysctl_sched_wakeup_granularity = 2000000UL;
 
-extern struct sched_class fair_sched_class;
-
 /**************************************************************
  * CFS operations on generic schedulable entities:
  */
@@ -1031,7 +1029,8 @@
 /*
  * All the scheduling class methods:
  */
-struct sched_class fair_sched_class __read_mostly = {
+static const struct sched_class fair_sched_class = {
+	.next			= &idle_sched_class,
 	.enqueue_task		= enqueue_task_fair,
 	.dequeue_task		= dequeue_task_fair,
 	.yield_task		= yield_task_fair,