RV1126 has five GPIOs groups - GPIO0 in PD_MMU and GPIO1-4
in PD_BUS.

In GPIO0, up to Lower C group GPIO0_C[3:0] is part of PMU
but rest of the groups from there are part of GRF.

Added pinctrl support for RV1126 and the pull, drv and schmitt
calculations are inferred from [1] authored by Jianqun Xu.

[1] https://github.com/rockchip-linux/kernel/blob/develop-4.19/drivers/pinctrl/pinctrl-rockchip.c

Cc: linux-gpio@vger.kernel.org
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Link: https://lore.kernel.org/r/20220818124132.125304-8-jagan@edgeble.aiSigned-off-by: Linus Walleij <linus.walleij@linaro.org>