pinctrl/rockchip: drop the gpio related codes

With the patch to separate the gpio driver from the pinctrl driver, now
the pinctrl-rockchip can drop the gpio related codes now.

Signed-off-by: Jianqun Xu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Linus Walleij <[email protected]>

Author: jayxurockchip