[IPV6]: Use the {DEFINE|REF}_PROTO_INUSE infrastructure

Trivial patch to make "tcpv6,udpv6,udplitev6,rawv6" protocols uses the
fast "inuse sockets" infrastructure

Each protocol use then a static percpu var, instead of a dynamic one.
This saves some ram and some cpu cycles

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 8344d8c..ee1cc3f 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -970,6 +970,8 @@
 
 /* ------------------------------------------------------------------------ */
 
+DEFINE_PROTO_INUSE(udpv6)
+
 struct proto udpv6_prot = {
 	.name		   = "UDPv6",
 	.owner		   = THIS_MODULE,
@@ -991,6 +993,7 @@
 	.compat_setsockopt = compat_udpv6_setsockopt,
 	.compat_getsockopt = compat_udpv6_getsockopt,
 #endif
+	REF_PROTO_INUSE(udpv6)
 };
 
 static struct inet_protosw udpv6_protosw = {