regulator: bd71815: switch to using devm_fwnode_gpiod_get()

I would like to stop exporting OF-specific devm_gpiod_get_from_of_node()
so that gpiolib can be cleaned a bit, so let's switch to the generic
fwnode property API.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/20220903-gpiod_get_from_of_node-remove-v1-8-b29adfb27a6c@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>