QTI DDR cooling device

The DDR cooling device will be used to place a DDR frequency vote. This
cooling device will be used in those cases where all the subsystem's are
thermally throttled and DDR has to be operated with a minimum performance
level. This cooling device vote can ensure the same.

Properties:
- compatible:
	Usage: required
	Value type: <string>
	Definition: should be "qcom,ddr-cooling-device"

Cooling device node:
- qcom,freq-table:
	Usage: required
	Value type: <u32 array>
	Definition: List of available DDR frequencies.

-#cooling-cells:
	Usage: required
	Value type: <integer>
	Definition: Must be 2. Needed for of_thermal as cooling device
			identifier. Please refer to
			<devicetree/bindings/thermal/thermal.txt> for more
			details.

- interconnects:
	Usage: required
	Definition: Pairs of phandles and interconnect provider specificers
			to denote the edge source and destination ports of
			the desired interconnect path. Please refer to
			<devicetree/bindings/interconnect/interconnect.txt>
			for more details.

- qcom,bus-width:
	Usage: required
	Definition: Provides the bus width for DDR.

Example:
	qcom,ddr-cdev {
		compatible = "qcom,ddr-cooling-device";
		qcom,freq-table = <200000>,
                                  <451000>,
                                  <768000>,
                                  <1017000>,
                                  <2092000>,
                                  <2736000>;
		qcom,bus-width = <4>;
		#cooling-cells = <2>;
		interconnects = <&mc_virt MASTER_LLCC &mc_virt SLAVE_EBI1>;
        };