pinctrl: Add pinctrl driver for the RK805 PMIC

RK805 is one of Rockchip PMICs family, it has 2 output only GPIOs.

This driver is also designed for other Rockchip PMICs to expend.
Different PMIC maybe have different pin features, for example,
RK816 has one pin which can be used for TS or GPIO(input/out).
The mainly difference between PMICs pins are pinmux, direction
and output value, that is 'struct rk805_pin_config'.

Signed-off-by: Joseph Chen <chenjh@rock-chips.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>