ASoC: Intel: bytcr_rt5651: switch to using devm_fwnode_gpiod_get()

devm_fwnode_get_index_gpiod_from_child() is going away as the name is
too unwieldy, let's switch to using the new devm_fwnode_gpiod_get().

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://lore.kernel.org/r/20200103011754.GA260926@dtor-ws


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