[SCTP]: Add back the code that accounted for FORWARD_TSN parameter in INIT.

Some recent changes completely removed accounting for the FORWARD_TSN
parameter length in the INIT and INIT-ACK chunk.  This is wrong and
should be restored.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/sm_make_chunk.c

@@ -210,6 +210,9 @@ struct sctp_chunk *sctp_make_init(const struct sctp_association *asoc,
 	chunksize = sizeof(init) + addrs_len + SCTP_SAT_LEN(num_types);
 	chunksize += sizeof(ecap_param);
 
+	if (sctp_prsctp_enable)
+		chunksize += sizeof(prsctp_param);
+
 	/* ADDIP: Section 4.2.7:
 	 *  An implementation supporting this extension [ADDIP] MUST list
 	 *  the ASCONF,the ASCONF-ACK, and the AUTH  chunks in its INIT and
@@ -369,6 +372,9 @@ struct sctp_chunk *sctp_make_init_ack(const struct sctp_association *asoc,
 	if (asoc->peer.ecn_capable)
 		chunksize += sizeof(ecap_param);
 
+	if (sctp_prsctp_enable)
+		chunksize += sizeof(prsctp_param);
+
 	if (sctp_addip_enable) {
 		extensions[num_ext] = SCTP_CID_ASCONF;
 		extensions[num_ext+1] = SCTP_CID_ASCONF_ACK;