gpio: lp87565: Add support for GPIO

Add driver for lp87565 PMIC family GPIOs. Three GPIOs are supported
and can be configured in Open-drain output or Push-pull output.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>