dt-bindings: net: remove reference to fixed link support

Contrary to what the Device Tree binding indicates, the binding for the
PPv2 network device currently doesn't provide any fixed link
functionality. This commit adjusts the Device Tree binding documentation
accordingly.

Reported-by: Russell King - ARM Linux <linux@armlinux.org.uk>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/net/marvell-pp2.txt

@@ -27,9 +27,7 @@ Optional properties (port):
 
 - marvell,loopback: port is loopback mode
 - phy: a phandle to a phy node defining the PHY address (as the reg
-  property, a single integer). Note: if this property isn't present,
-  then fixed link is assumed, and the 'fixed-link' property is
-  mandatory.
+  property, a single integer).
 
 Example: