mm/shmem.c: use helper macro K()

Use helper macro K() to improve code readability.  No functional
modification involved.

Link: https://lkml.kernel.org/r/20230804012559.2617515-5-zhangpeng362@huawei.comSigned-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/shmem.c

@@ -3864,8 +3864,7 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
 	struct mempolicy *mpol;
 
 	if (sbinfo->max_blocks != shmem_default_max_blocks())
-		seq_printf(seq, ",size=%luk",
-			sbinfo->max_blocks << (PAGE_SHIFT - 10));
+		seq_printf(seq, ",size=%luk", K(sbinfo->max_blocks));
 	if (sbinfo->max_inodes != shmem_default_max_inodes())
 		seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
 	if (sbinfo->mode != (0777 | S_ISVTX))