pinctrl: add pinctrl_add_gpio_ranges function

Often GPIO ranges are added in batch, so create a special
function for that.

Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>