dt-bindings: Add device-tree bindings for BT power driver

* Bluetooth Controller

Bluetooth controller communicates with the Bluetooth Host using HCI Transport

layer. HCI Transport layer can be based on UART or USB serial communication

protocol.

Required properties:

- compatible: "qcom,<chip>"

	chip: Should be set to one of the following:

		qcom,qca6174

		qcom,wcn3990

		qcom,qca6390

		qcom,qca6490

	- qcom,bt-reset-gpio: GPIO pin to bring BT Controller out of reset

Optional properties:

	- qcom,bt-vdd-pa-supply: Bluetooth VDD PA regulator handle

	- qcom,bt-vdd-io-supply: Bluetooth VDD IO regulator handle

	- qcom,bt-vdd-ldo-supply: Bluetooth VDD LDO regulator handle. Kept under

		optional parameters as some of the chipsets doesn't require ldo

		or it may use from same vddio.

	- qcom,bt-vdd-xtal-supply: Bluetooth VDD XTAL regulator handle

	- qcom,bt-vdd-core-supply: Bluetooth VDD CORE regulator handle

	- qcom,bt-vdd-asd-supply: Bluetooth VDD regulator handle for antenna switch

    diversity.

	- qcom,bt-chip-pwd-supply: Chip power down gpio is required when bluetooth

		module and other modules like wifi co-exist in a singe chip and

		shares a common gpio to bring chip out of reset.

  - qcom,<supply>-config: Specifies voltage/current levels for supply. Should specified

                          in pairs (min, max), units uV.  There can be optional

                          load in curr, unit uA. Last entry specifies if the retention

                          mode is supported for the regulator.

Example:

	bluetooth: bt_qca6490 {

		compatible = "qcom,qca6390", "qcom,qca6490";

		pinctrl-names = "default";

		pinctrl-0 = <&bt_en_sleep>;

		qcom,bt-reset-gpio = <&tlmm 21 0>; /* BT_EN */

		qcom,bt-vdd-aon-supply = <&pm8150_s6>;

		qcom,bt-vdd-dig-supply = <&pm8009_s2>;

		qcom,bt-vdd-rfa1-supply = <&pm8150_s5>;

		qcom,bt-vdd-rfa2-supply = <&pm8150a_s8>;

		qcom,bt-vdd-asd-supply = <&pm8150_l16>;

		qcom,bt-vdd-aon-config = <950000 950000 0  1>;

		qcom,bt-vdd-dig-config = <950000 952000 0  1>;

		qcom,bt-vdd-rfa1-config = <1900000 1900000 0  1>;

		qcom,bt-vdd-rfa2-config = <1350000 1350000 0  1>;

		qcom,bt-vdd-asd-config = <3024000 3304000 10000  0>;

	};