sched: Change cgroup task scheduler policy

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


CVE: NA

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Added restrictions on modifying task scheduling policies:
1. task cannot be changed from offline to online.
2. When the scheduling policy of parent task is modified, the scheduling policy
   of all child node tasks is changed to be the same as that of the parent node.

Signed-off-by: Zheng Zucheng <zhengzucheng@huawei.com>
Reviewed-by: Chen Hui <judy.chenhui@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>