netfilter: ip6t_LOG: Fix a typo in a comment

s/_IPT_LOG_H/_IP6T_LOG_H/

While at it add some surrounding space to ease reading.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter_ipv6/ip6t_LOG.h

@@ -17,4 +17,4 @@ struct ip6t_log_info {
 	char prefix[30];
 };
 
-#endif /*_IPT_LOG_H*/
+#endif /* _IP6T_LOG_H */