Add gpio offset into "gpio-range-cells" property. It's used to support
sparse pinctrl range in gpio chip.
Signed-off-by: NHaojian Zhuang <haojian.zhuang@linaro.org>
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>