pinctrl: pistachio: Correct the fwnode_irq_get() return value check

fwnode_irq_get() may return all possible signed values, such as Linux
error code or 0. Fix the code to handle this properly.

Fixes: 1074e1d2 ("pinctrl: pistachio: Switch to use fwnode instead of")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220908094323.31965-1-andriy.shevchenko@linux.intel.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-pistachio.c

@@ -1374,8 +1374,14 @@ static int pistachio_gpio_register(struct pistachio_pinctrl *pctl)
 
 		ret = fwnode_irq_get(child, 0);
 		if (ret < 0) {
+			fwnode_handle_put(child);
+			dev_err(pctl->dev, "Failed to retrieve IRQ for bank %u\n", i);
+			goto err;
+		}
+		if (!ret) {
 			fwnode_handle_put(child);
 			dev_err(pctl->dev, "No IRQ for bank %u\n", i);
+			ret = -EINVAL;
 			goto err;
 		}
 		irq = ret;