dt-bindings: net: broadcom-bluetooth: Add VBAT and VDDIO supplies

The Broadcom Bluetooth chips have two power inputs, VBAT and VDDIO.
The former provides overall power for the chip, while the latter powers
the I/O pins and buffers.

This patch adds properties for the two so we can describe the power
supply relationships.
Reviewed-by: NRob Herring <robh@kernel.org>
Tested-by: NOndrej Jirman <megous@megous.com>
Signed-off-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

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

@@ -23,6 +23,8 @@ Optional properties:
    - "extclk": deprecated, replaced by "txco"
    - "txco": external reference clock (not a standalone crystal)
    - "lpo": external low power 32.768 kHz clock
+ - vbat-supply: phandle to regulator supply for VBAT
+ - vddio-supply: phandle to regulator supply for VDDIO
 
 
 Example: