commit 121b6a79 upstream.

The gpio-chip device attributes were never destroyed when the device was
removed.

Fix by using device_create_with_groups() to create the device attributes
of the chip class device.

Note that this also fixes the attribute-creation race with userspace.

Fixes: d8f388d8 ("gpio: sysfs interface")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[ luis: backported to 3.16:
  - file rename: drivers/gpio/gpiolib-sysfs.c -> drivers/gpio/gpiolib.c ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>