sched/rt: removed unneeded defintion

Impact: cleanup

This function no longer exists, so remove the defintion.
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/sched.h

@@ -258,8 +258,6 @@ static inline int select_nohz_load_balancer(int cpu)
 }
 #endif
 
-extern unsigned long rt_needs_cpu(int cpu);
-
 /*
  * Only dump TASK_* tasks. (0 for all tasks)
  */