PCUIF: rename tlli to msg_id

To confirm downlink IMMEDIATE ASSIGNMENT messages, we use the TLLI as an
identifier and the related record member is also called "tlli".
Unfortunately this is misleading since the message identifier does not
necessarly have to be a TLLI. It is just an implementation detail that
osmo-pcu uses the TLLI as a message identifier.

To make that clear, lets rename the tlli member (and variable and
parameter names where it is passed on) to "msg_id".

(Since this change only renames variables and struct members it will not
break compatibility with other programs that use the PCUIF)

Related: OS#5927
Depends: osmo-pcu.git I4a25039dfe329e68879bc68936e49c4b190625e6
Change-Id: I1db29d5b1920e351c452b798c3260654c2cbe0cb
diff --git a/pcu/PCUIF_Components.ttcn b/pcu/PCUIF_Components.ttcn
index 8a1207a..a6c5bae 100644
--- a/pcu/PCUIF_Components.ttcn
+++ b/pcu/PCUIF_Components.ttcn
@@ -140,7 +140,7 @@
 type record BTS_CCCH_Block {
 	uint8_t		bts_nr,
 	PCUIF_data	raw,
-	OCT4		tlli optional,
+	OCT4		msg_id optional,
 	charstring	imsi optional,
 	GsmRrMessage	rr_msg
 };
@@ -161,11 +161,11 @@
 template BTS_CCCH_Block tr_PCUIF_DATA_RR(template uint8_t bts_nr,
 					    template PCUIF_data raw,
 					    template GsmRrMessage rr_msg := ?,
-					    template OCT4 tlli := *,
+					    template OCT4 msg_id := *,
 					    template charstring imsi := *) := {
 	bts_nr := bts_nr,
 	raw := raw,
-	tlli := tlli,
+	msg_id := msg_id,
 	imsi := imsi,
 	rr_msg := rr_msg
 };
@@ -550,11 +550,11 @@
 
 		if (pcu_msg_rr.raw.sapi == PCU_IF_SAPI_PCH_DT) {
 			pch_dt := dec_PCUIF_pch_dt(pcu_msg_rr.raw.data);
-			pcu_msg_rr.tlli := pch_dt.tlli;
+			pcu_msg_rr.msg_id := pch_dt.msg_id;
 			pcu_msg_rr.imsi := pch_dt.imsi;
 			pcu_msg_rr.rr_msg := dec_GsmRrMessage(pch_dt.data);
 		} else {
-			pcu_msg_rr.tlli := omit;
+			pcu_msg_rr.msg_id := omit;
 			pcu_msg_rr.imsi := omit;
 			pcu_msg_rr.rr_msg := dec_GsmRrMessage(data);
 		}