dt-bindings: can: flexcan: add can wakeup property

This patch adds the wakeup-source boolean property.
Signed-off-by: NSean Nyekjaer <sean@geanix.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/fsl-flexcan.txt

@@ -39,6 +39,8 @@ Optional properties:
 		  0: clock source 0 (oscillator clock)
 		  1: clock source 1 (peripheral clock)
 
+- wakeup-source: enable CAN remote wakeup
+
 Example:
 
 	can@1c000 {