pinctrl: rockchip: Add 32bit writing function for rk3288 gpio0 pinctrl

There are no higher 16 writing corresponding bits for pmu_gpio0's
iomux/drive/pull at rk3288, need to read the value from register
firstly. Add the flag to distinguish it from normal registers.

Signed-off-by: David Wu <david.wu@rock-chips.com>