commit 01cca93a upstream.

Unregister gpiochip device (used to export information through sysfs)
before removing it internally. This way removal will reverse addition.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[ luis: backported to 3.16: used Johan's backport to 3.14 ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>