gpio: pxa: disable pinctrl calls for PXA3xx

The pxa3xx driver uses the pinctrl-single driver since a while which
does not implement a .gpio_set_direction() callback. The pinmux core
will simply return 0 in this case, and the pxa3xx gpio driver hence
believes the pinctrl driver did its job and returns as well.

This effectively makes pxa_gpio_direction_{input,output} no-ops.

To fix this, do not call into the pinctrl subsystem for the PXA3xx
platform for now. We can revert this once the pinctrl-single driver
learned to support setting pin directions.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>