gpio: gpio-kempld: Fix get_direction return value

This patch fixes an inverted return value of the gpio get_direction
function.

The wrong value causes the direction sysfs entry and GPIO debugfs file
to indicate incorrect GPIO direction settings. In some cases it also
prevents setting GPIO output values.

The problem is also present in all other stable kernel versions since
linux-3.12.

Cc: Stable <stable@vger.kernel.org> # v3.12+
Reported-by: Jochen Henneberg <jh@henneberg-systemdesign.com>
Signed-off-by: Michael Brunner <michael.brunner@kontron.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>