gpiolib: change a warning to debug message when failing to get gpio

It's the drivers responsibility to react on failure to get
the gpio descriptors and not the frameworks. Since there are
some common peripherals that may or may not have certain
pins connected to gpio lines, depending on the platform,
printing the warning there may end up generating useless bug
reports.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index dbddace..85f772c 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2447,7 +2447,7 @@
 	}
 
 	if (IS_ERR(desc)) {
-		dev_warn(dev, "lookup for GPIO %s failed\n", con_id);
+		dev_dbg(dev, "lookup for GPIO %s failed\n", con_id);
 		return desc;
 	}