pinctrl: airoha: Add support for EN7581 SoC

pinctrl: airoha: Add support for EN7581 SoC

Introduce pinctrl driver for EN7581 SoC. Current EN7581 pinctrl driver
supports the following functionalities:
- pin multiplexing
- pin pull-up, pull-down, open-drain, current strength,
  {input,output}_enable, output_{low,high}
- gpio controller
- irq controller

Tested-by: Benjamin Larsson <benjamin.larsson@genexis.eu>
Co-developed-by: Benjamin Larsson <benjamin.larsson@genexis.eu>
Signed-off-by: Benjamin Larsson <benjamin.larsson@genexis.eu>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/20241023-en7581-pinctrl-v9-5-afb0cbcab0ec@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>