memcg: add restrict to swap to cgroup1

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I7CGGT


CVE: NA

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The memsw can't limit the usage of swap space. Add memory.swap.max
interface to limit the difference value of memsw.usage and memory.usage.
Since a page may occupy both swap entry and a swap cache page, this value
is not exactly equal to swap.usage.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>