ARM: ux500: Enable probing of pinctrl through Device Tree

The Nomadik GPIO controller now relies on Nomadik pinctrl, however
the pinctrl driver is not currently started by any ux500 platform.
This is requred or GPIOs do not work at all.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>