superio: Add SMSC SIO1007 driver

The SMSC SIO1007 superio chipset integrates two ns16550 compatible
serial ports for legacy applications, 16 GPIO pins and some other
functionalities like power management.

This adds a simple driver to enable serial port and handle GPIO.

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