dt-bindings: net: bluetooth: Add device tree bindings for QTI chip wcn6750

This patch enables regulators and gpios for the Qualcomm Bluetooth wcn6750
controller.

Signed-off-by: Venkata Lakshmi Narayana Gubba <gubbaven@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>