gpio: mockup: fix direction values

The comment in linux/gpio/driver.h says:

 @get_direction: returns direction for signal "offset", 0=out, 1=in

We got those switched at some point. Fix the values.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>