pinctrl: nuvoton: Reduce use of OF-specific APIs

pinctrl: nuvoton: Reduce use of OF-specific APIs

Some drivers are using device property APIs along with OF-specific ones.
At the same time few of the latter can be converted to device property
calls. Reduce use of OF-specific APIs in order to bring a bit more consistency
into the drivers.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/20250318105932.2090926-6-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>