mm/userswap: provide cpu info in userfault msg

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8KESX


CVE: NA

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The uffd_msg.reserved3 field is used to transfer the CPU information of
the PF.

Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>