[IPV4] UDP,UDPLITE: Sparse: {__udp4_lib,udp,udplite}_err() are of void.

Fix following sparse warnings:
| net/ipv4/udp.c:421:2: warning: returning void-valued expression
| net/ipv4/udplite.c:38:2: warning: returning void-valued expression

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/net/ipv4/udplite.c b/net/ipv4/udplite.c
index f5baeb3..001b881 100644
--- a/net/ipv4/udplite.c
+++ b/net/ipv4/udplite.c
@@ -35,7 +35,7 @@
 
 static void udplite_err(struct sk_buff *skb, u32 info)
 {
-	return __udp4_lib_err(skb, info, udplite_hash);
+	__udp4_lib_err(skb, info, udplite_hash);
 }
 
 static	struct net_protocol udplite_protocol = {