mm/swapfile: use new way to fix broken kabi in swap_info_struct

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I645JI



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Commit 46d673d7 ("mm/swapfile: fix broken kabi in swap_info_struct")
uses KABI_EXTEND to fix kabi broken problem, but this is not the safest
way, so use new way to fix this prolem.

Introduce new struct swap_extend_info that contains extend info of swap,
meanwhile use KABI_USE to repalce memory space reserved by KABI_RESERVER.

Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Reviewed-by: zhangjialin <zhangjialin11@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>