Binding for a ST pll clock driver.

This binding uses the common clock binding[1].
Base address is located to the parent node. See clock binding[2]

[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
[2] Documentation/devicetree/bindings/clock/st/st,clkgen.txt

Required properties:

- compatible : shall be:
	"st,clkgen-pll0"
	"st,clkgen-pll0-a0"
	"st,clkgen-pll0-c0"
	"st,clkgen-pll1"
	"st,clkgen-pll1-c0"
	"st,stih407-clkgen-plla9"
	"st,stih418-clkgen-plla9"

- #clock-cells : From common clock binding; shall be set to 1.

- clocks : From common clock binding

- clock-output-names : From common clock binding.

Example:

	clockgen-a9@92b0000 {
		compatible = "st,clkgen-c32";
		reg = <0x92b0000 0xffff>;

		clockgen_a9_pll: clockgen-a9-pll {
			#clock-cells = <1>;
			compatible = "st,stih407-clkgen-plla9";

			clocks = <&clk_sysin>;

			clock-output-names = "clockgen-a9-pll-odf";
		};
	};
