nat: Return the SCCP Connection again...

We will reset the multiplex in a DLCX message and then
we can reset the multiplex as well...even if the MGCP
connection is staying open. or at least this is a theory.

The MSC likes to leave a connection open during CallControl
when hanging up early enough in the process.
diff --git a/openbsc/tests/bsc-nat/bsc_nat_test.c b/openbsc/tests/bsc-nat/bsc_nat_test.c
index 12141ef..e547ee4 100644
--- a/openbsc/tests/bsc-nat/bsc_nat_test.c
+++ b/openbsc/tests/bsc-nat/bsc_nat_test.c
@@ -432,14 +432,14 @@
 		abort();
 	}
 
-	if (bsc_mgcp_find_con(nat, 12) != con) {
+	if (bsc_mgcp_find_con(nat, 12) != sccp_con) {
 		fprintf(stderr, "Didn't find the connection\n");
 		abort();
 	}
 
 	sccp_con->msc_timeslot = 0;
 	sccp_con->bsc_timeslot = 0;
-	if (bsc_mgcp_find_con(nat, 1) != con) {
+	if (bsc_mgcp_find_con(nat, 1) != sccp_con) {
 		fprintf(stderr, "Didn't find the connection\n");
 		abort();
 	}