Add pinctrl driver for RK3528.
Imported from vendor U-Boot linux-6.1-stan-rkr5 tag with adjustments
to use regmap_update_bits().
Signed-off-by: Steven Liu <steven.liu@rock-chips.com>
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>