neigh: remove dynamic neigh table registration support

Currently there are only three neigh tables in the whole kernel:
arp table, ndisc table and decnet neigh table. What's more,
we don't support registering multiple tables per family.
Therefore we can just make these tables statically built-in.

Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 16acb59..205e147 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1292,7 +1292,7 @@
 
 void __init arp_init(void)
 {
-	neigh_table_init(&arp_tbl);
+	neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
 
 	dev_add_pack(&arp_packet_type);
 	arp_proc_init();