gpio: add gpio offset in gpio range cells property

Add gpio offset into "gpio-range-cells" property. It's used to support
sparse pinctrl range in gpio chip.

Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index a71a54a..892040a 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -203,22 +203,11 @@
 		if (!pctldev)
 			break;
 
-		/*
-		 * This assumes that the n GPIO pins are consecutive in the
-		 * GPIO number space, and that the pins are also consecutive
-		 * in their local number space. Currently it is not possible
-		 * to add different ranges for one and the same GPIO chip,
-		 * as the code assumes that we have one consecutive range
-		 * on both, mapping 1-to-1.
-		 *
-		 * TODO: make the OF bindings handle multiple sparse ranges
-		 * on the same GPIO chip.
-		 */
 		ret = gpiochip_add_pin_range(chip,
 					     pinctrl_dev_get_devname(pctldev),
-					     0, /* offset in gpiochip */
 					     pinspec.args[0],
-					     pinspec.args[1]);
+					     pinspec.args[1],
+					     pinspec.args[2]);
 
 		if (ret)
 			break;