ASCI: Allow usage of rtp_stream with other FSM

Allow the caller of rtp_stream_alloc() to define what events will be
dispatched to the parent FSM. This allows other state machines to use
rtp_stream. It is required for using RTP stream process with VGCS FSM.

Drop the unused parent_call_leg member.

Change-Id: I0991927b6d00da08dfd455980645e68281a73a9e
Related: OS#4854
diff --git a/src/libmsc/call_leg.c b/src/libmsc/call_leg.c
index b078c77..d0dc642 100644
--- a/src/libmsc/call_leg.c
+++ b/src/libmsc/call_leg.c
@@ -303,7 +303,8 @@
 		return -EIO;
 	}
 
-	cl->rtp[dir] = rtp_stream_alloc(cl, dir, call_id, for_trans);
+	cl->rtp[dir] = rtp_stream_alloc(cl->fi, CALL_LEG_EV_RTP_STREAM_GONE, CALL_LEG_EV_RTP_STREAM_ADDR_AVAILABLE,
+					CALL_LEG_EV_RTP_STREAM_ESTABLISHED, dir, call_id, for_trans);
 	OSMO_ASSERT(cl->rtp[dir]);
 	return 0;
 }