libmsc/mncc_call.c: fix uninitialized access of stack memory

Change-Id: I5f561d9682c9fb87e4837430063095ef2cb7bd5f
Fixes: CID#198405
diff --git a/src/libmsc/mncc_call.c b/src/libmsc/mncc_call.c
index 6ea4024..5ca91d0 100644
--- a/src/libmsc/mncc_call.c
+++ b/src/libmsc/mncc_call.c
@@ -199,7 +199,7 @@
 void mncc_call_detach_rtp_stream(struct mncc_call *mncc_call)
 {
 	struct rtp_stream *rtps = mncc_call->rtps;
-	struct osmo_sockaddr_str clear;
+	struct osmo_sockaddr_str clear = { 0 };
 	if (!rtps)
 		return;
 	mncc_call->rtps = NULL;