dt-bindings: net: bluetooth: Add device tree bindings for QCA chip QCA6390

This patch adds compatible string for the QCA chip QCA6390.
Signed-off-by: Rocky Liao <rjliao@codeaurora.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

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

@@ -13,6 +13,7 @@ Required properties:
    * "qcom,wcn3990-bt"
    * "qcom,wcn3991-bt"
    * "qcom,wcn3998-bt"
+   * "qcom,qca6390-bt"
 
 Optional properties for compatible string qcom,qca6174-bt: