pinctrl: sunxi: Move setting of mux to irq type

With level triggered interrupt mask / unmask will get called for each
interrupt, doing the somewhat expensive mux setting on each unmask thus is
not a good idea. Instead add a request_resources callback and do it there.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>