ISDN: hysdn, fix potential NULL dereference

Stanse found that lp is dereferenced earlier than checked for being
NULL in hysdn_rx_netpkt. Move the initialization below the test.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: netdev@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/hysdn/hysdn_net.c

@@ -187,12 +187,13 @@ void
 hysdn_rx_netpkt(hysdn_card * card, unsigned char *buf, unsigned short len)
 {
 	struct net_local *lp = card->netif;
-	struct net_device *dev = lp->dev;
+	struct net_device *dev;
 	struct sk_buff *skb;
 
 	if (!lp)
 		return;		/* non existing device */
 
+	dev = lp->dev;
 	dev->stats.rx_bytes += len;
 
 	skb = dev_alloc_skb(len);