gpio: of: Don't return 0 on dt_gpio_count()

It's unusual to have error checking like (ret <= 0) in cases when
counting GPIO resources. In case when it's mandatory we propagate the
error (-ENOENT), otherwise we don't use the result.

This makes consistent behaviour across all possible variants called in
gpiod_count().
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -3122,10 +3122,10 @@ static int dt_gpio_count(struct device *dev, const char *con_id)
 				 gpio_suffixes[i]);
 
 		ret = of_gpio_named_count(dev->of_node, propname);
-		if (ret >= 0)
+		if (ret > 0)
 			break;
 	}
-	return ret;
+	return ret ? ret : -ENOENT;
 }
 
 static int platform_gpio_count(struct device *dev, const char *con_id)