[PATCH] prism54: Remove redundant assignment

The last patch I sent in ("prism54: Free skb after disabling
interrupts") included a redundant NULL assignment. Thanks to Herbert
Xu for pointing it out.
Signed-off-by: NDaniel Drake <dsd@gentoo.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/prism54/islpci_eth.c

@@ -244,7 +244,6 @@ islpci_eth_transmit(struct sk_buff *skb, struct net_device *ndev)
 	priv->statistics.tx_dropped++;
 	spin_unlock_irqrestore(&priv->slock, flags);
 	dev_kfree_skb(skb);
-	skb = NULL;
 	return err;
 }