pinctrl: rockchip: Add rv1108 recalculated iomux support

The pins from GPIO1A0 to GPIO1B1 are special, need to recalculate
iomux. And the register offset is larger than the u8 range, so changed
to u32.

Signed-off-by: David Wu <david.wu@rock-chips.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>