Add GPIO support for max77650 mfd device. This PMIC exposes a single
GPIO line.
Signed-off-by: NBartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>