This provides GPIO support over SCMI.  It is built on top of the
pinctrl-scmi driver.  A typical device tree entry might look like
this:

    gpio1 {
        compatible = "scmi-pinctrl-gpio";
        gpio-controller;
        #gpio-cells = <2>;
        ngpios = <10>;
        gpio-ranges = <&scmi_pinctrl 0 8 4>,
                      <&scmi_pinctrl 4 12 1>,
                      <&scmi_pinctrl 5 15 1>,
                      <&scmi_pinctrl 6 17 4>;
        pinctrl-names = "default";
        pinctrl-0 = <&i2c2_pins>;
    };

In this GPIO driver the one thing which is different is that in the
gpio-ranges the first numbers which represent how the pins are exposed
to the users have to start at zero and it can't have gaps.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Peng Fan <peng.fan@nxp.com>