Switch the driver to the generic version of gpiod API (and away from
OF-specific variant), so that we can stop exporting
devm_gpiod_get_from_of_node().

Link: https://lore.kernel.org/r/Y3KMEZFv6dpxA+Gv@google.comSigned-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Acked-by: NPali Rohár <pali@kernel.org>