staging: wlags49_h2: 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 <segooon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/wlags49_h2/wl_netdev.c

@@ -1586,7 +1586,7 @@ void wl_wds_device_dealloc( struct wl_private *lp )
                 dev_wds->flags &= ~( IFF_UP | IFF_RUNNING );
             }
 
-            kfree( dev_wds );
+            free_netdev(dev_wds);
             lp->wds_port[count].dev = NULL;
         }
     }