dt-bindings: net: can: m_can: Add Documentation for stb-gpios

The CAN transceiver on some boards has an STB pin which is
used to control its standby mode. Add an optional property
stb-gpios to toggle the same.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

Documentation/devicetree/bindings/net/can/m_can.txt

@@ -48,6 +48,8 @@ Optional Subnode:
 			  that can be used for CAN/CAN-FD modes. See
 			  Documentation/devicetree/bindings/net/can/can-transceiver.txt
 			  for details.
+stb-gpios		: gpio node to toggle the STB (standby) signal on the transceiver
+
 Example:
 SoC dtsi:
 m_can1: can@20e8000 {