pinctrl: pxa: add pxa25x architecture

Add the pxa25x architecture, which is a pxa2xx with 85 pins. The
registers spacing, and pins logic is common to pxa2xx, only the pins and
their alternate function are specific to pxa25x.

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