ipv6: Remove some pointless conditionals before kfree_skb()

Remove some pointless conditionals before kfree_skb().

The semantic match that finds the problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression E;
@@
- if (E)
- 	kfree_skb(E);
+ kfree_skb(E);
// </smpl>

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ipv6_sockglue.c

@@ -218,8 +218,7 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 			if (opt)
 				sock_kfree_s(sk, opt, opt->tot_len);
 			pktopt = xchg(&np->pktoptions, NULL);
-			if (pktopt)
-				kfree_skb(pktopt);
+			kfree_skb(pktopt);
 
 			sk->sk_destruct = inet_sock_destruct;
 			/*