mmap: userswap: fix some format issues

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4AHP2


CVE: NA

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Fix some format issues in mm/mmap.c.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>