sched: Clear idle_stamp when unthrottle offline tasks

hulk inclusion
category: bugfix
bugzilla: 51828, https://gitee.com/openeuler/kernel/issues/I4K96G
CVE: NA

--------------------------------

When unthrottle offline tasks successfully, we should clear
idle_stamp.
Signed-off-by: NZhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: NZheng Zucheng <zhengzucheng@huawei.com>
Reviewed-by: NChen Hui <judy.chenhui@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

kernel/sched/fair.c

@@ -7144,6 +7144,7 @@ done: __maybe_unused;
 
 #ifdef CONFIG_QOS_SCHED
 	if (unthrottle_qos_cfs_rqs(cpu_of(rq))) {
+		rq->idle_stamp = 0;
 		goto again;
 	}
 #endif