sched: extract walk_tg_tree(), fix

fix:

 kernel/sched.c: In function '__rt_schedulable':
 kernel/sched.c:8771: error: implicit declaration of function 'walk_tg_tree'
 kernel/sched.c:8771: error: 'tg_nop' undeclared (first use in this function)
 kernel/sched.c:8771: error: (Each undeclared identifier is reported only once
 kernel/sched.c:8771: error: for each function it appears in.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -1387,7 +1387,7 @@ static inline void dec_cpu_load(struct rq *rq, unsigned long load)
 	update_load_sub(&rq->load, load);
 }
 
-#if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(SCHED_RT_GROUP_SCHED)
+#if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(CONFIG_RT_GROUP_SCHED)
 typedef int (*tg_visitor)(struct task_group *, void *);
 
 /*