DT doc: net: cpsw mac-address is optional

mac-address is an optional property. If no mac-address is set, a random
mac-address will be generated.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/cpsw.txt

@@ -29,10 +29,10 @@ Slave Properties:
 Required properties:
 - phy_id		: Specifies slave phy id
 - phy-mode		: See ethernet.txt file in the same directory
-- mac-address		: See ethernet.txt file in the same directory
 
 Optional properties:
 - dual_emac_res_vlan	: Specifies VID to be used to segregate the ports
+- mac-address		: See ethernet.txt file in the same directory
 
 Note: "ti,hwmods" field is used to fetch the base address and irq
 resources from TI, omap hwmod data base during device registration.