irda: remove some pointless conditionals before kfree_skb()

Remove some pointless conditionals before kfree_skb().

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/irda/sir_dev.c b/drivers/net/irda/sir_dev.c
index c23d211..803c0be 100644
--- a/drivers/net/irda/sir_dev.c
+++ b/drivers/net/irda/sir_dev.c
@@ -780,8 +780,7 @@
 
 static void sirdev_free_buffers(struct sir_dev *dev)
 {
-	if (dev->rx_buff.skb)
-		kfree_skb(dev->rx_buff.skb);
+	kfree_skb(dev->rx_buff.skb);
 	kfree(dev->tx_buff.head);
 	dev->rx_buff.head = dev->tx_buff.head = NULL;
 	dev->rx_buff.skb = NULL;