net: axienet: delete unneeded test before of_node_put

Of_node_put supports NULL as its argument, so the initial test is not
necessary.

Suggested by Uwe Kleine-König.

The semantic patch that fixes this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression e;
@@

-if (e)
   of_node_put(e);
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -1630,8 +1630,7 @@ static int axienet_of_remove(struct platform_device *op)
 	axienet_mdio_teardown(lp);
 	unregister_netdev(ndev);
 
-	if (lp->phy_node)
-		of_node_put(lp->phy_node);
+	of_node_put(lp->phy_node);
 	lp->phy_node = NULL;
 
 	iounmap(lp->regs);