QTI QRTR MHI Dev transport binding

- compatible:
	Usage: required
	Value type: <stringlist>
	Definition: must be "qcom,qrtr-mhi-dev"

- qcom,net-id:
	Usage: optional
	Value type: <u32>
	Definition: indicates what subnet this transport belongs to. Should be
		    passed into the qrtr core logic to determine if forwarding
		    is needed on this endpoint.

- qcom,low-latency:
	Usage: optional
	Value type: <bool>
	Definition: indicates whether this transport receiving thread needs to
		    be set to realtime priority for enhanced performance.

= EXAMPLE
The following example represents the qrtr mhi dev transport node on a device
configured as a pcie endpoint and needs to forward data from the host to a
modem co-processor.

	qcom,mhi_dev_qrtr {
		compatible = "qcom,qrtr-mhi-dev";
		qcom,net-id = <3>;
		qcom,low-latency;
	};