Binding for Imagination Technologies MIPS Boston clock sources.

This binding uses the common clock binding[1].

[1] Documentation/devicetree/bindings/clock/clock-bindings.txt

The device node must be a child node of the syscon node corresponding to the
Boston system's platform registers.

Required properties:
- compatible : Should be "img,boston-clock".
- #clock-cells : Should be set to 1.
  Values available for clock consumers can be found in the header file:
    <dt-bindings/clock/boston-clock.h>

Example:

	system-controller@17ffd000 {
		compatible = "img,boston-platform-regs", "syscon";
		reg = <0x17ffd000 0x1000>;

		clk_boston: clock {
			compatible = "img,boston-clock";
			#clock-cells = <1>;
		};
	};

	uart0: uart@17ffe000 {
		/* ... */
		clocks = <&clk_boston BOSTON_CLK_SYS>;
	};