pinctrl: nomadik: decomission non-DT boot path

After the patches deleting the last board registering this
pin controller as a platform device has been deleted,
proceed to remove the non-DT boot patch and depend on
OF being available and the device to be coming up by
a DT node.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>