[IPV6] use appropriate __alignof__() for mibs.

net/ipv6/af_inet6.c

@@ -671,10 +671,10 @@ static int __init init_ipv6_mibs(void)
 			   __alignof__(struct ipv6_mib)) < 0)
 		goto err_ip_mib;
 	if (snmp6_mib_init((void **)icmpv6_statistics, sizeof (struct icmpv6_mib),
-			   __alignof__(struct ipv6_mib)) < 0)
+			   __alignof__(struct icmpv6_mib)) < 0)
 		goto err_icmp_mib;
 	if (snmp6_mib_init((void **)udp_stats_in6, sizeof (struct udp_mib),
-			   __alignof__(struct ipv6_mib)) < 0)
+			   __alignof__(struct udp_mib)) < 0)
 		goto err_udp_mib;
 	return 0;