irda: remove some pointless conditionals before kfree_skb()

Remove some pointless conditionals before kfree_skb().
Signed-off-by: NWei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/irda/sir_dev.c

@@ -780,7 +780,6 @@ static int sirdev_alloc_buffers(struct sir_dev *dev)
 
 static void sirdev_free_buffers(struct sir_dev *dev)
 {
-	if (dev->rx_buff.skb)
 	kfree_skb(dev->rx_buff.skb);
 	kfree(dev->tx_buff.head);
 	dev->rx_buff.head = dev->tx_buff.head = NULL;