sctp: make ecn flag per netns and endpoint

This patch is to add ecn flag for both netns_sctp and sctp_endpoint,
net->sctp.ecn_enable is set 1 by default, and ep->ecn_enable will
be initialized with net->sctp.ecn_enable.

asoc->peer.ecn_capable will be set during negotiation only when
ep->ecn_enable is set on both sides.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 2d47adc..b48ffe8 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1254,6 +1254,9 @@ static int __net_init sctp_defaults_init(struct net *net)
 	/* Disable AUTH by default. */
 	net->sctp.auth_enable = 0;
 
+	/* Enable ECN by default. */
+	net->sctp.ecn_enable = 1;
+
 	/* Set SCOPE policy to enabled */
 	net->sctp.scope_policy = SCTP_SCOPE_POLICY_ENABLE;