sched: Move SMP-only variable into the SMP section

This also fixes the following compilation warning on !SMP:

  CC kernel/sched/fair.o
  kernel/sched/fair.c:218:36: warning: 'max_load_balance_interval' defined but not used [-Wunused-variable]
Signed-off-by: NHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Reviewed-by: NVincent Guittot <vincent.guittot@linaro.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4F2754A0.9090306@ct.jp.nec.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

kernel/sched/fair.c

@@ -215,8 +215,6 @@ calc_delta_mine(unsigned long delta_exec, unsigned long weight,
 
 const struct sched_class fair_sched_class;
 
-static unsigned long __read_mostly max_load_balance_interval = HZ/10;
-
 /**************************************************************
  * CFS operations on generic schedulable entities:
  */
@@ -3086,6 +3084,8 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp
  * Fair scheduling class load-balancing methods:
  */
 
+static unsigned long __read_mostly max_load_balance_interval = HZ/10;
+
 /*
  * pull_task - move a task from a remote runqueue to the local runqueue.
  * Both runqueues must be locked.