gpio: nomadik: Finish conversion to use firmware node APIs

gpio: nomadik: Finish conversion to use firmware node APIs

Previously driver got a few updates in order to replace OF APIs by
respective firmware node, however it was not finished to the logical
end, e.g., some APIs that has been used are still require OF node
to be passed. Finish that job by converting leftovers to use firmware
node APIs.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20240302173401.217830-1-andy.shevchenko@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>