dt-bindings: net: Add TI WiLink shared transport binding

Add serial slave device binding for the TI WiLink series of Bluetooth/FM/GPS
devices.
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: netdev@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Documentation/devicetree/bindings/net/ti,wilink-st.txt

+TI WiLink 7/8 (wl12xx/wl18xx) Shared Transport BT/FM/GPS devices
+
+TI WiLink devices have a UART interface for providing Bluetooth, FM radio,
+and GPS over what's called "shared transport". The shared transport is
+standard BT HCI protocol with additional channels for the other functions.
+
+These devices also have a separate WiFi interface as described in
+wireless/ti,wlcore.txt.
+
+This bindings follows the UART slave device binding in
+../serial/slave-device.txt.
+
+Required properties:
+ - compatible: should be one of the following:
+    "ti,wl1271-st"
+    "ti,wl1273-st"
+    "ti,wl1831-st"
+    "ti,wl1835-st"
+    "ti,wl1837-st"
+
+Optional properties:
+ - enable-gpios : GPIO signal controlling enabling of BT. Active high.
+ - vio-supply : Vio input supply (1.8V)
+ - vbat-supply : Vbat input supply (2.9-4.8V)
+
+Example:
+
+&serial0 {
+	compatible = "ns16550a";
+	...
+	bluetooth {
+		compatible = "ti,wl1835-st";
+		enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>;
+	};
+};