V3s SoC features only a pin controller (for the lack of CPUs part).

Add a driver for this controller.
Signed-off-by: NIcenowy Zheng <icenowy@aosc.xyz>
Acked-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>