Binding for SPI slave to control si5518 clock and respective clock buffer.

SPI includes two chip selects, CS0 is used for si5518 clock and CS1 is used for clock buffer.

Required properties:
- compatible:	  Should contain "qcom,si5518-clk"
- reg:		  Should contain base register location and length
- spi-max-frequency: Specifies maximum SPI clock frequency,
		     Units - Hz. Definition as per
		     Documentation/devicetree/bindings/spi/spi-bus.txt

Example:

	&qupv3_se14_spi {
		status = "ok";
		spidev@0 {
			compatible = "qcom,si5518-clk";
			spi-max-frequency = <1000000>;
			reg = <0>;
		};
		spidev@1 {
			compatible = "qcom,si5518-clk";
			spi-max-frequency = <1000000>;
			reg = <1>;
		};

	};
