f2fs: fix wrong unlock_page call

This patch removes wrongly called unlock_page.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -837,7 +837,6 @@ static int f2fs_write_data_page(struct page *page,
 	/* we should bypass data pages to proceed the kworkder jobs */
 	if (unlikely(f2fs_cp_error(sbi))) {
 		SetPageError(page);
-		unlock_page(page);
 		goto out;
 	}