bsc: improve error log for "RSL for unknown Dchan"

The failure verdict includes the RSL message that could not be
associated with a handling component, but ttcn_logformat does not format
that message. Add an identical log() that gets formatted nicely.

Change-Id: Ibb8f60671e78075492783cba560a8229ba5a380b

library/RSL_Emulation.ttcn

@@ -612,6 +612,8 @@ function main(boolean bts_role := true) runs on RSL_Emulation_CT {
 				log("Storing an RSL message in the waiting queue");
 				WaitingQueue := WaitingQueue & { rx_rsl };
 			} else {
+				log("Error: RSL for unknown Dchan (streamId ", rx_rsl.streamId, ", chan_nr ",
+					   rx_rsl.rsl.ies[0].body.chan_nr, "): ", rx_rsl);
 				setverdict(fail, "RSL for unknown Dchan");
 				mtc.stop;
 			}