pinctrl: ocelot: Add Sparx5 SoC support

This add support for Sparx5 pinctrl, using the ocelot drives as
basis. It adds pinconfig support as well, as supported by the
platform.
Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200615133242.24911-6-lars.povlsen@microchip.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>