[IPV6]: cleanup_ipv6_mibs cannot be __exit, since it is called on the ipv6_init error path.

net/ipv6/af_inet6.c

@@ -684,7 +684,7 @@ static int __init init_ipv6_mibs(void)
 	
 }
 
-static void __exit cleanup_ipv6_mibs(void)
+static void cleanup_ipv6_mibs(void)
 {
 	kfree_percpu(ipv6_statistics[0]);
 	kfree_percpu(ipv6_statistics[1]);