Atmel PWM controller

Required properties:
  - compatible: should be one of:
    - "atmel,at91sam9rl-pwm"
    - "atmel,sama5d3-pwm"
    - "atmel,sama5d2-pwm"
    - "microchip,sam9x60-pwm"
  - reg: physical base address and length of the controller's registers
  - #pwm-cells: Should be 3. See pwm.yaml in this directory for a
    description of the cells format.

Example:

	pwm0: pwm@f8034000 {
		compatible = "atmel,at91sam9rl-pwm";
		reg = <0xf8034000 0x400>;
		#pwm-cells = <3>;
	};

	pwmleds {
		compatible = "pwm-leds";

		d1 {
			label = "d1";
			pwms = <&pwm0 3 5000 0>
			max-brightness = <255>;
		};

		d2 {
			label = "d2";
			pwms = <&pwm0 1 5000 1>
			max-brightness = <255>;
		};
	};