staging: octeon: use free_netdev(netdev) instead of kfree()

It is not guaranteed that free_netdev() is macro.
Freeing netdev without free_netdev() leads to net, tx leaks.
I might lead to dereferencing freed pointer.
Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Acked-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/octeon/ethernet.c

@@ -670,7 +670,7 @@ static int __init cvm_oct_init_module(void)
 
 			if (register_netdev(dev) < 0) {
 				pr_err("Failed to register ethernet device for POW\n");
-				kfree(dev);
+				free_netdev(dev);
 			} else {
 				cvm_oct_device[CVMX_PIP_NUM_INPUT_PORTS] = dev;
 				pr_info("%s: POW send group %d, receive group %d\n",
@@ -756,12 +756,12 @@ static int __init cvm_oct_init_module(void)
 			}
 
 			if (!dev->netdev_ops) {
-				kfree(dev);
+				free_netdev(dev);
 			} else if (register_netdev(dev) < 0) {
 				pr_err("Failed to register ethernet device "
 					 "for interface %d, port %d\n",
 					 interface, priv->port);
-				kfree(dev);
+				free_netdev(dev);
 			} else {
 				cvm_oct_device[priv->port] = dev;
 				fau -=
@@ -815,7 +815,7 @@ static void __exit cvm_oct_cleanup_module(void)
 
 			cvm_oct_tx_shutdown_dev(dev);
 			unregister_netdev(dev);
-			kfree(dev);
+			free_netdev(dev);
 			cvm_oct_device[port] = NULL;
 		}
 	}