GSUP_Types: Fix tr_GSUP_IMSI params

Change-Id: Ifeff47d35df53f4238bc1556bdee037e62e9d892
diff --git a/library/GSUP_Types.ttcn b/library/GSUP_Types.ttcn
index ef98175..739dcbc 100644
--- a/library/GSUP_Types.ttcn
+++ b/library/GSUP_Types.ttcn
@@ -507,7 +507,7 @@
 	ies := ies
 }
 
-template GSUP_PDU tr_GSUP_IMSI(template GSUP_MessageType msgt := ?, template hexstring imsi) := {
+template (present) GSUP_PDU tr_GSUP_IMSI(template (present) GSUP_MessageType msgt := ?, template (present) hexstring imsi := ?) := {
 	msg_type := msgt,
 	ies := { tr_GSUP_IE_IMSI(imsi), * }
 }
@@ -715,7 +715,7 @@
 	}
 }
 
-template GSUP_IE tr_GSUP_IE_IMSI(template hexstring imsi) := {
+template (present) GSUP_IE tr_GSUP_IE_IMSI(template (present) hexstring imsi := ?) := {
 	tag := OSMO_GSUP_IMSI_IE,
 	len := ?,
 	val := {