[SCTP]: Tie ADD-IP and AUTH functionality as required by spec.

ADD-IP spec requires AUTH. It is, in fact, dangerous without AUTH.
So, disable ADD-IP functionality if the peer claims to support
ADD-IP, but not AUTH.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 47e54f8..448f713 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -1543,6 +1543,7 @@
 		__u8    asconf_capable;  /* Does peer support ADDIP? */
 		__u8    prsctp_capable;  /* Can peer do PR-SCTP? */
 		__u8	auth_capable;	 /* Is peer doing SCTP-AUTH? */
+		__u8	addip_capable;	 /* Can peer do ADD-IP */
 
 		__u32   adaptation_ind;	 /* Adaptation Code point. */