sctp: implement sender-side procedures for SSN Reset Request Parameter

This patch is to implement sender-side procedures for the Outgoing
and Incoming SSN Reset Request Parameter described in rfc6525 section
5.1.2 and 5.1.3.

It is also add sockopt SCTP_RESET_STREAMS in rfc6525 section 6.3.2
for users.

Note that the new asoc member strreset_outstanding is to make sure
only one reconf request chunk on the fly as rfc6525 section 5.1.1
demands.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/sctp.h

@@ -193,6 +193,12 @@ void sctp_remaddr_proc_exit(struct net *net);
  */
 int sctp_offload_init(void);
 
+/*
+ * sctp/stream.c
+ */
+int sctp_send_reset_streams(struct sctp_association *asoc,
+			    struct sctp_reset_streams *params);
+
 /*
  * Module global variables
  */