x86: minnowmax: Remove smsc47x superio codes

On Intel BayTrail SoC, there is a legacy UART (I/O 0x3f8) integrated
into the SoC which is enabled by the FSP. Remove the smsc47x superio
initialization codes.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>