f2fs: fix to clear page private flag

Commit 28bc106b ("f2fs: support revoking atomic written pages")
forgot to clear page private flag correctly, fix it.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -227,6 +227,7 @@ static int __revoke_inmem_pages(struct inode *inode,
 		if (drop || recover)
 			ClearPageUptodate(page);
 		set_page_private(page, 0);
+		ClearPagePrivate(page);
 		f2fs_put_page(page, 1);
 
 		list_del(&cur->list);