ipv4: icmp: use percpu allocation

Get rid of nr_cpu_ids and use modern percpu allocation.

Note that the sockets themselves are not yet allocated
using NUMA affinity.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 24945ce..7283f4d3 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -48,7 +48,8 @@
 	struct hlist_head	*fib_table_hash;
 	struct sock		*fibnl;
 
-	struct sock		**icmp_sk;
+	struct sock  * __percpu	*icmp_sk;
+
 	struct inet_peer_base	*peers;
 	struct tcpm_hash_bucket	*tcp_metrics_hash;
 	unsigned int		tcp_metrics_hash_log;