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

Freeing netdev without free_netdev() leads to net, tx leaks.
I might lead to dereferencing freed pointer.

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

@@
struct net_device* dev;
@@

-kfree(dev)
+free_netdev(dev)

Signed-off-by: Vasiliy Kulikov <[e-mail]>
Acked-by: Denis Kirjanov <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/slicoss/slicoss.c

···
 		slic_global.num_slic_cards--;
 		slic_card_cleanup(card);
 	}
-	kfree(dev);
+	free_netdev(dev);
 	pci_release_regions(pcidev);
 }