net: constify struct net_protocol

Remove long removed "inet_protocol_base" declaration.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 60093be..c557f1f 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -924,7 +924,7 @@
 };
 
 /* Register with IP layer.  */
-static struct net_protocol sctp_protocol = {
+static const struct net_protocol sctp_protocol = {
 	.handler     = sctp_rcv,
 	.err_handler = sctp_v4_err,
 	.no_policy   = 1,