net:dl2k: Modify the code style escaping the warning

modify the code style in order to removing the following warning
when excute the script checkpatch.pl
WARNING: space prohibited between function name and open parenthesis '('
Signed-off-by: Huang Zijiang <huang.zijiang@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/dlink/dl2k.c

@@ -843,9 +843,9 @@ rio_free_tx (struct net_device *dev, int irq)
 				  desc_to_dma(&np->tx_ring[entry]),
 				  skb->len, PCI_DMA_TODEVICE);
 		if (irq)
-			dev_kfree_skb_irq (skb);
+			dev_kfree_skb_irq(skb);
 		else
-			dev_kfree_skb (skb);
+			dev_kfree_skb(skb);
 
 		np->tx_skbuff[entry] = NULL;
 		entry = (entry + 1) % TX_RING_SIZE;