pinctrl: ocelot: add optional shared reset

On the LAN9668 there is a shared reset line which affects GPIO, SGPIO
and the switch core. Add support for this shared reset line.

Signed-off-by: Michael Walle <michael@walle.cc>
Tested-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20220420191926.3411830-3-michael@walle.cc


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