commit 49d2ca84 upstream.

Fix memory leak in the gpio sysfs interface due to failure to drop
reference to device returned by class_find_device when setting the
gpio-line polarity.

Fixes: 07697461 ("gpiolib: add support for changing value polarity
in sysfs")
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>