pinctrl/lantiq: pinconf uses port instead of pin

The XWAY pinctrl driver invalidly uses the port and not the pin
number to work out the registers and bits to be set for the
opendrain and pullup/down resistors.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>