pinctrl/rockchip: add error handling for pull/drive register getters

Add error handling for the pull and driver register getters in preparation
for RK3588 support.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Heiko Stübner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220422170920.401914-13-sebastian.reichel@collabora.com


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