sched/core: Remove unused variable from set_user_nice()

This commit left behind an unused variable:

  5443a0be ("sched: Use fair:prio_changed() instead of ad-hoc implementation") left behind an unused variable.

  kernel/sched/core.c: In function 'set_user_nice':
  kernel/sched/core.c:4507:16: warning: variable 'delta' set but not used
    int old_prio, delta;
                ^~~~~
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 5443a0be ("sched: Use fair:prio_changed() instead of ad-hoc implementation")
Link: https://lkml.kernel.org/r/20191219140314.1252-1-cai@lca.pwSigned-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

@@ -4504,7 +4504,7 @@ static inline int rt_effective_prio(struct task_struct *p, int prio)
 void set_user_nice(struct task_struct *p, long nice)
 {
 	bool queued, running;
-	int old_prio, delta;
+	int old_prio;
 	struct rq_flags rf;
 	struct rq *rq;
 
@@ -4538,7 +4538,6 @@ void set_user_nice(struct task_struct *p, long nice)
 	set_load_weight(p, true);
 	old_prio = p->prio;
 	p->prio = effective_prio(p);
-	delta = p->prio - old_prio;
 
 	if (queued)
 		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);