Tegra SoC PWFM controller

Required properties:
- compatible: For Tegra20, must contain "nvidia,tegra20-pwm".  For Tegra30,
  must contain "nvidia,tegra30-pwm".  Otherwise, must contain
  "nvidia,<chip>-pwm", plus one of the above, where <chip> is tegra114,
  tegra124, tegra132, or tegra210.
- reg: physical base address and length of the controller's registers
- #pwm-cells: should be 2. See pwm.txt in this directory for a description of
  the cells format.
- clocks: Must contain one entry, for the module clock.
  See ../clocks/clock-bindings.txt for details.
- resets: Must contain an entry for each entry in reset-names.
  See ../reset/reset.txt for details.
- reset-names: Must include the following entries:
  - pwm

Example:

	pwm: pwm@7000a000 {
		compatible = "nvidia,tegra20-pwm";
		reg = <0x7000a000 0x100>;
		#pwm-cells = <2>;
		clocks = <&tegra_car 17>;
		resets = <&tegra_car 17>;
		reset-names = "pwm";
	};
