[IPV6] UDPLITE: Sparse: Declare non-static symbols in header.

Fix the following sparse warnings:
| net/ipv6/udplite.c:45:14: warning: symbol 'udplitev6_prot' was not declared. Should it be static?
| net/ipv6/udplite.c:80:12: warning: symbol 'udplitev6_init' was not declared. Should it be static?
| net/ipv6/udplite.c:99:6: warning: symbol 'udplitev6_exit' was not declared. Should it be static?

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

net/ipv6/udp_impl.h

@@ -5,6 +5,7 @@
 #include <net/protocol.h>
 #include <net/addrconf.h>
 #include <net/inet_common.h>
+#include <net/transp_v6.h>
 
 extern int  	__udp6_lib_rcv(struct sk_buff *, struct hlist_head [], int );
 extern void 	__udp6_lib_err(struct sk_buff *, struct inet6_skb_parm *,