hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4G4S5

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When files cgroup is enabled, it's will leads syscall performance
regression in UnixBench. Add a helper files_cgroup_enabled() and
use it to control if use files cgroup, wen can use cgroup_disable=files
in cmdline to disable files cgroup.

syscall of UnixBench (large is better)
enable files cgroup:            2868.5
disable files cgroup:           3177.0
disable config of files cgroup: 3186.5
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NTao Hou <houtao1@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Conflicts:
	Documentation/admin-guide/kernel-parameters.txt
Signed-off-by: NLu Jialin <lujialin4@huawei.com>
Reviewed-by: Nweiyang wang <wangweiyang2@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>