Mediatek MT5870 PWM controller

Required properties:

 - compatible: must be "mediatek,mt5870-pwm"
 - reg: physical base address and length for this controller
 - #pwm-cells: must be 2. See pwm.txt in this directory for a description of
   the cell format.
 - clocks: XTAL


Example:

	pwm: pwm {
		compatible = "mediatek,mt5870-pwm";
		reg = <0 0x1f206400 0 0x200>;
		#pwm-cells = <2>;
	};
