Super I/O chips require a password to unlock access to the I/O ports.
Add a driver that pokes the password and registers the appropriate GPIO
and Watchdog devices as well as a regmap reflecting the Super I/O chip.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>