[IPV6] UDP,UDPLITE: Sparse: {__udp6_lib,udp,udplite}_err() are of void.

Fix following sparse warnings:
| net/ipv6/udp.c:262:2: warning: returning void-valued expression
| net/ipv6/udplite.c:29:2: warning: returning void-valued expression
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

net/ipv6/udp.c

@@ -259,7 +259,7 @@ static __inline__ void udpv6_err(struct sk_buff *skb,
 				 struct inet6_skb_parm *opt, int type,
 				 int code, int offset, __be32 info     )
 {
-	return __udp6_lib_err(skb, opt, type, code, offset, info, udp_hash);
+	__udp6_lib_err(skb, opt, type, code, offset, info, udp_hash);
 }
 
 int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)

net/ipv6/udplite.c

@@ -26,7 +26,7 @@ static void udplitev6_err(struct sk_buff *skb,
 			  struct inet6_skb_parm *opt,
 			  int type, int code, int offset, __be32 info)
 {
-	return __udp6_lib_err(skb, opt, type, code, offset, info, udplite_hash);
+	__udp6_lib_err(skb, opt, type, code, offset, info, udplite_hash);
 }
 
 static struct inet6_protocol udplitev6_protocol = {