SSM2518 audio amplifier

This device supports I2C only.

Required properties:
  - compatible : Must be "adi,ssm2518"
  - reg : the I2C address of the device. This will either be 0x34 (ADDR pin low)
	or 0x35 (ADDR pin high)

Optional properties:
  - gpios : GPIO connected to the nSD pin. If the property is not present it is
	        assumed that the nSD pin is hardwired to always on.

Example:

	ssm2518: ssm2518@34 {
		compatible = "adi,ssm2518";
		reg = <0x34>;
		gpios = <&gpio 5 0>;
	};
