isdn: 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/isdn/capi/capi.c b/drivers/isdn/capi/capi.c
index 1b5bf87..3e468d2 100644
--- a/drivers/isdn/capi/capi.c
+++ b/drivers/isdn/capi/capi.c
@@ -277,7 +277,7 @@
 	list_del(&mp->list);
 	write_unlock_irqrestore(&capiminor_list_lock, flags);
 
-	if (mp->ttyskb) kfree_skb(mp->ttyskb);
+	kfree_skb(mp->ttyskb);
 	mp->ttyskb = NULL;
 	skb_queue_purge(&mp->inqueue);
 	skb_queue_purge(&mp->outqueue);