pinctrl: nuvoton: Use pinconf_generic_dt_node_to_map_all()

Use the pinconf_generic_dt_node_to_map_all() helper instead of
open-coding the same operation, to avoid having to provide custom
pinctrl_ops.dt_node_to_map() callbacks.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/r/81e9ab48f78d63153b23a163b3349b3059d2b7fc.1692871558.git.geert+renesas@glider.be


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>