Convert the RT5668 to use GPIO descriptors and drop the
legacy GPIO headers.

We remove the global GPIO number from the platform data,
but it is still possible to create board files using GPIO
descriptor tables, if desired.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230817-descriptors-asoc-rt-v2-3-02fa2ca3e5b0@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>