o af_netlink: netlink_proto_init has to be core_initcall

As it has to happen before pktsched_init, that is called from
net_dev_init that is a subsys_initcall, making it the same
init level as netlink_proto_init, that ends up being called
_after_ net_dev_init, so when pktsched_init is called it finds
rtnetlink_links[PF_UNSPEC] as null and therefore not sets
the ->dumpit entry for RTM_GETQDISC (and the others too):
b00m, rtnetlink_rcv sends a failure message to tc.

net/netlink/af_netlink.c

@@ -1082,7 +1082,7 @@ static void __exit netlink_proto_exit(void)
        remove_proc_entry("net/netlink", NULL);
 }
 
-subsys_initcall(netlink_proto_init);
+core_initcall(netlink_proto_init);
 module_exit(netlink_proto_exit);
 
 MODULE_LICENSE("GPL");