dt-bindings: pinctrl: Add support for Amlogic A4 SoC

Add the dt-bindings for Amlogic pin controller, and add a new
dt-binding header file which document the GPIO bank names of
Amlogic A4 SoC.

Signed-off-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/20250212-amlogic-pinctrl-v5-1-282bc2516804@amlogic.com


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