ipv6: constify inet6_protocol structures

The inet6_protocol structure is only passed as the first argument to
inet6_add_protocol or inet6_del_protocol, both of which are declared as
const.  Thus the inet6_protocol structure itself can be const.

Also drop __read_mostly where present on the newly const structures.

Done with the help of Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_gre.c

@@ -1080,7 +1080,7 @@ static void ip6gre_fb_tunnel_init(struct net_device *dev)
 }
 
 
-static struct inet6_protocol ip6gre_protocol __read_mostly = {
+static const struct inet6_protocol ip6gre_protocol = {
 	.handler     = gre_rcv,
 	.err_handler = ip6gre_err,
 	.flags       = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,

net/ipv6/tcp_ipv6.c

@@ -1945,7 +1945,7 @@ struct proto tcpv6_prot = {
 	.diag_destroy		= tcp_abort,
 };
 
-static struct inet6_protocol tcpv6_protocol = {
+static const struct inet6_protocol tcpv6_protocol = {
 	.early_demux	=	tcp_v6_early_demux,
 	.early_demux_handler =  tcp_v6_early_demux,
 	.handler	=	tcp_v6_rcv,

net/ipv6/udp.c

@@ -1448,7 +1448,7 @@ int compat_udpv6_getsockopt(struct sock *sk, int level, int optname,
 }
 #endif
 
-static struct inet6_protocol udpv6_protocol = {
+static const struct inet6_protocol udpv6_protocol = {
 	.early_demux	=	udp_v6_early_demux,
 	.early_demux_handler =  udp_v6_early_demux,
 	.handler	=	udpv6_rcv,