nilfs2: remove page_address() from nilfs_add_link

In preparation for removing kmap from directory handling, use
offset_in_page() to calculate 'from'.  Matches ext2.

Link: https://lkml.kernel.org/r/20231127143036.2425-5-konishi.ryusuke@gmail.comSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/nilfs2/dir.c

@@ -493,7 +493,7 @@ int nilfs_add_link(struct dentry *dentry, struct inode *inode)
 	return -EINVAL;
 
 got_it:
-	from = (char *)de - (char *)page_address(page);
+	from = offset_in_page(de);
 	to = from + rec_len;
 	err = nilfs_prepare_chunk(page, from, to);
 	if (err)