pinctrl: single: create new gpio function range

Since gpio driver could create gpio range in DTS, it could invoke
pinctrl_request_gpio(). In the pinctrl-single driver, it needs to
configure pins with gpio function mode.

A new gpio function range should be created in DTS file in below.

pinctrl-single,gpio-range = <phandle pin_offset nr_pins gpio_func>;

range: gpio-range {
	#pinctrl-single,gpio-range-cells = <3>;
};

The gpio-ranges property is used in gpio driver and the
pinctrl-single,gpio-range property is used in pinctrl-single driver.

1. gpio-ranges is used for gpio driver in below.
   gpio-ranges = <phandle gpio_offset_in_chip pin_offset nr_pins>
	gpio-ranges = < &pmx0 0 89 1 &pmx0 1 89 1 &pmx0 2 90 1
			&pmx0 3 90 1 &pmx0 4 91 1 &pmx0 5 92 1>;

2. gpio driver could get pin offset from gpio-ranges property.
   pinctrl-single driver could get gpio function mode from gpio_func
   that is stored in @gpiofuncs list in struct pcs_device.
   This new pinctrl-single,gpio-range is used as complement for
   gpio-ranges property in gpio driver.

Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>