Documentation: gpio: Add APM X-Gene SoC GPIO controller DTS binding

Documentation for APM X-Gene SoC GPIO controller DTS binding.

Signed-off-by: Feng Kan <fkan@apm.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
1 file changed