x86: Adjust board_final_cleanup() order

Call board_final_cleanup() before write_tables(), so that anything
done in board_final_cleanup() on a normal boot path is also done
on an S3 resume path.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stefan Roese <sr@denx.de>