endp: do not cache cfg pointer

There is no obvious reason why we would want to complicate the code by
caching pointers, since pointer traversal is probably not a performance
bottleneck, and if it is we should rather take a look at our dozens of
linked lists first..

Change-Id: I2456ba63598f76200d53e00223abf60bb36a49c0
diff --git a/src/libosmo-mgcp/mgcp_sdp.c b/src/libosmo-mgcp/mgcp_sdp.c
index 077ac96..a36c6d2 100644
--- a/src/libosmo-mgcp/mgcp_sdp.c
+++ b/src/libosmo-mgcp/mgcp_sdp.c
@@ -576,7 +576,7 @@
 	OSMO_ASSERT(addr);
 
 	/* FIXME: constify endp and conn args in get_net_donwlink_format_cb() */
-	endp->cfg->get_net_downlink_format_cb((struct mgcp_endpoint *)endp,
+	endp->trunk->cfg->get_net_downlink_format_cb((struct mgcp_endpoint *)endp,
 					      &codec, &fmtp_extra,
 					      (struct mgcp_conn_rtp *)conn);
 
@@ -601,7 +601,7 @@
 
 		payload_types[0] = payload_type;
 		if (mgcp_conn_rtp_is_osmux(conn))
-			local_port = endp->cfg->osmux_port;
+			local_port = endp->trunk->cfg->osmux_port;
 		else
 			local_port = conn->end.local_port;
 		rc = add_audio(sdp, payload_types, 1, local_port);