gpiolib: friendly debug information for consumer

"failed" maybe makes observer confuse when a consumer can not
lookup, so change to a friendly information.
Signed-off-by: Wang Dongsheng <dongsheng.wang@hxt-semitech.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -3689,7 +3689,7 @@ struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
 	}
 
 	if (IS_ERR(desc)) {
-		dev_dbg(dev, "lookup for GPIO %s failed\n", con_id);
+		dev_dbg(dev, "No GPIO consumer %s found\n", con_id);
 		return desc;
 	}