sched: Unthrottle qos cfs rq when free a task group

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I3ZX4D


CVE: NA

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When freeing a taskgroup, we will free cfs rqs of the group, even if cfs rqs
have been throttled, otherwise it will cause a Use-After-Free Bug. Therefore
before freeing a taskgroup, we should unthrottle all cfs rqs belonging to
the taskgroup.

Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Zheng Zucheng <zhengzucheng@huawei.com>
Reviewed-by: Chen Hui <judy.chenhui@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>