commit ebbeba12 upstream.

Fix attribute-creation race with userspace by using the default group
to create also the contingent gpio device attributes.

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:
  - all changes in drivers/gpio/gpiolib.c
  - adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>