The GPIO library expects the drivers to return -ENOTSUPP in some cases
and not using analogue POSIX code. Make the driver to follow this.
Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: William Breathitt Gray <wbg@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>