psi: fix wrong iteration in iterate_groups

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I562O9


CVE: NA
backport: openEuler-22.03-LTS

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It is different to get the cgroup that is used to update psi info in
cgroup v1 and cgroup v2.

task_cgroup can only used in cgroup v1, so add branch to achieve this.

Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>