nat: Forward extra state and the message to the USSD provider

Forward the SCCP state and the data to the USSD provider,
also mark the connection as local.
diff --git a/openbsc/src/nat/bsc_nat.c b/openbsc/src/nat/bsc_nat.c
index fb4c150..daabf09 100644
--- a/openbsc/src/nat/bsc_nat.c
+++ b/openbsc/src/nat/bsc_nat.c
@@ -856,10 +856,8 @@
 					}
 
 					/* hand data to a side channel */
-					if (bsc_check_ussd(con, parsed, msg) == 1) {
-						/* we are going to take over the connection */
-						/* TODO: */
-					}
+					if (bsc_check_ussd(con, parsed, msg) == 1) 
+						con->con_local = 2;
 				}
 
 				con_bsc = con->bsc;