pinctrl: actions: Add Actions Semi S700 pinctrl driver

Add pinctrl and gpio driver for Actions Semi S700 SoC. The driver
supports pinctrl, pinmux, pinconf, gpio and interrupt functionalities
through a range of registers common to both gpio driver and pinctrl driver.

Signed-off-by: Parthiban Nallathambi <pn@denx.de>
Signed-off-by: Saravanan Sekar <sravanhome@gmail.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>