pinctrl: Ingenic: Add pinctrl driver for X1500.

Add support for probing the pinctrl-ingenic driver on the
X1500 Soc from Ingenic.

Signed-off-by: Zhou Yanjie <zhouyanjie@zoho.com>
Link: https://lore.kernel.org/r/1563076436-5338-7-git-send-email-zhouyanjie@zoho.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>