gpio: sysfs: fix memory leak in gpiod_export_link

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: a4177ee7f1a8 ("gpiolib: allow exported GPIO nodes to be named
using sysfs links")
Cc: stable <[e-mail]> # v2.6.32
Signed-off-by: Johan Hovold <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpiolib-sysfs.c

···
 		if (tdev != NULL) {
 			status = sysfs_create_link(&dev->kobj, &tdev->kobj,
 						name);
+			put_device(tdev);
 		} else {
 			status = -ENODEV;
 		}