pinctrl: pistachio: fix leaked of_node references

The call to of_get_child_by_name returns a node pointer with refcount
incremented thus it must be explicitly decremented after the last
usage.

Detected by coccinelle with the following warnings:
./drivers/pinctrl/pinctrl-pistachio.c:1422:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 1360, but without a corresponding object release within this function.
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-pistachio.c

@@ -1367,6 +1367,7 @@ static int pistachio_gpio_register(struct pistachio_pinctrl *pctl)
 		if (!of_find_property(child, "gpio-controller", NULL)) {
 			dev_err(pctl->dev,
 				"No gpio-controller property for bank %u\n", i);
+			of_node_put(child);
 			ret = -ENODEV;
 			goto err;
 		}
@@ -1374,6 +1375,7 @@ static int pistachio_gpio_register(struct pistachio_pinctrl *pctl)
 		irq = irq_of_parse_and_map(child, 0);
 		if (irq < 0) {
 			dev_err(pctl->dev, "No IRQ for bank %u: %d\n", i, irq);
+			of_node_put(child);
 			ret = irq;
 			goto err;
 		}