[PATCH] gpio: just plain warning when nonexisting gpio requested

["Enrico Weigelt, metux IT consult" <info@xxxxxxxxx>]

From: Enrico Weigelt <info@xxxxxxxxx>

When trying to export an nonexisting gpio ID, the kernel prints
outs a big warning w/ stacktrace, sounding like a huge problem.
In fact it's a pretty normal situation, like file or device not
found.

So, just print a more relaxed warning instead.

Signed-off-by: Enrico Weigelt <info@xxxxxxxxx>
---
 drivers/gpio/gpiolib.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 3ee99d0..06eeedd 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1,4 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/bitmap.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -121,7 +124,7 @@ struct gpio_desc *gpio_to_desc(unsigned gpio)
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
 	if (!gpio_is_valid(gpio))
-		WARN(1, "invalid GPIO %d\n", gpio);
+		pr_warn("invalid GPIO %d\n", gpio);
 
 	return NULL;
 }
-- 
1.9.1