net: constify struct inet6_protocol

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 64f011c..364bfc7 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1152,7 +1152,7 @@
 #endif
 };
 
-static struct inet6_protocol dccp_v6_protocol = {
+static const struct inet6_protocol dccp_v6_protocol = {
 	.handler	= dccp_v6_rcv,
 	.err_handler	= dccp_v6_err,
 	.flags		= INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,