gpio: rockchip: add support for rk3588

Add V2.1 rockchip gpio controller type, which is part of the
RK3588 SoC.

Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>