Use helper macro SZ_1K to do the size conversion to make code more
consistent in this file. Minor readability improvement.

Link: https://lkml.kernel.org/r/20220901120030.63318-3-linmiaohe@huawei.comSigned-off-by: NMiaohe Lin <linmiaohe@huawei.com>
Reviewed-by: NMuchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>