Documentation: driver-api: Move gpio.rst to gpio/index.rst

To make space for more files in the GPIO section, create a
Documentation/driver-api/gpio/ directory.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2 files changed