bindings: add support for qcom,ucsi-glink

QTI UCSI binding

This binding describes the Qualcomm Technologies, Inc. UCSI device. UCSI

handles the communication between OPM on the Application processor and PPM

which is charger firmware running on the remote subsystem (e.g. DSP) over

PMIC Glink.

Refer to Documentation/devicetree/bindings/soc/qcom/qcom,pmic-glink.txt for

information on "qcom,pmic_glink" device which is used in the example below.

- compatible:

	Usage: required

	Value type: <stringlist>

	Definition: must be "qcom,ucsi-glink"

= EXAMPLE

&soc {

	qcom,pmic_glink {

		...

		qcom,ucsi {

			compatible = "qcom,ucsi-glink";

		};

		...

	};

};