dt-bindings: net: bluetooth: Add device tree bindings for QTI chip WCN3991

Add compatible string for the Qualcomm WCN3991 Bluetooth controller
Signed-off-by: NVenkata Lakshmi Narayana Gubba <gubbaven@codeaurora.org>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt

@@ -11,6 +11,7 @@ Required properties:
  - compatible: should contain one of the following:
    * "qcom,qca6174-bt"
    * "qcom,wcn3990-bt"
+   * "qcom,wcn3991-bt"
    * "qcom,wcn3998-bt"
 
 Optional properties for compatible string qcom,qca6174-bt:
@@ -30,6 +31,7 @@ Optional properties for compatible string qcom,wcn399x-bt:
 
  - max-speed: see Documentation/devicetree/bindings/serial/slave-device.txt
  - firmware-name: specify the name of nvm firmware to load
+ - clocks: clock provided to the controller
 
 Examples:
 
@@ -56,5 +58,6 @@ serial@898000 {
 		vddch0-supply = <&vreg_l25a_3p3>;
 		max-speed = <3200000>;
 		firmware-name = "crnv21.bin";
+		clocks = <&rpmhcc RPMH_RF_CLK2>;
 	};
 };