Nuvoton NAU8315 Mono Class-D Amplifier

Required properties:
- compatible   : "nuvoton,nau8315"
                 "nuvoton,nau8318"

Optional properties:
- enable-gpios : GPIO specifier for the chip's device enable input(EN) pin.
        If this option is not specified then driver does not manage
        the pin state (e.g. chip is always on).

Example:

#include <dt-bindings/gpio/gpio.h>

nau8315 {
	compatible = "nuvoton,nau8315";
	enable-gpios = <&gpio1 5 GPIO_ACTIVE_HIGH>;
};

nau8318 {
	compatible = "nuvoton,nau8318";
	enable-gpios = <&gpio1 5 GPIO_ACTIVE_HIGH>;
};