gpio: sysfs: fix memory leak in gpiod_export_link

commit 0f303db0 upstream.

Fix memory leak in the gpio sysfs interface due to failure to drop
reference to device returned by class_find_device when creating a link.

Fixes: a4177ee7 ("gpiolib: allow exported GPIO nodes to be named
using sysfs links")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[lizf: Backported to 3.4: adjust filename]
Signed-off-by: Zefan Li <lizefan@huawei.com>

drivers/gpio/gpiolib.c

@@ -825,6 +825,7 @@ int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
 		if (tdev != NULL) {
 			status = sysfs_create_link(&dev->kobj, &tdev->kobj,
 						name);
+			put_device(tdev);
 		} else {
 			status = -ENODEV;
 		}