msc: Only kill connections belonging to the given MSC

When a MSC connection drops, only kill the connections that
belong to the given MSC and not all other connections.
diff --git a/openbsc/src/osmo-bsc/osmo_bsc_sccp.c b/openbsc/src/osmo-bsc/osmo_bsc_sccp.c
index cc4eedf..1410cc6 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_sccp.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_sccp.c
@@ -272,8 +272,10 @@
 {
 	struct osmo_bsc_sccp_con *con, *tmp;
 
-	llist_for_each_entry_safe(con, tmp, &active_connections, entry)
-		bsc_sccp_force_free(con);
+	llist_for_each_entry_safe(con, tmp, &active_connections, entry) {
+		if (con->msc->msc_con == msc_con)
+			bsc_sccp_force_free(con);
+	}
 }
 
 static int handle_msc_signal(unsigned int subsys, unsigned int signal,