pinctrl: meson: implement the gpio_chip get_direction callback

Implement the get_direction callback so we read the direction from the
actual GPIO controller register. This is recommended by the gpio_chip
kernel doc.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20200417183349.1283092-2-martin.blumenstingl@googlemail.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>