pinctrl: rockchip: add support for rk3568

RK3568 SoCs have 5 gpio controllers, each gpio has 32 pins. GPIO supports
set iomux, pull, drive strength and schmitt.
Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Link: https://lore.kernel.org/r/20210319081441.368358-1-jay.xu@rock-chips.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>