pcu: TC_mt_ping_pong: Request UL TBF on last DL ACK

Let's test the code path where UL TBF is requested through DL ACK/NACK
here, since we already test the usual UL TBF through CCCH approach in
most tests.

rlc_mode is changed to ACKED since that's the mode we are using so far
in tests.

Change-Id: I5a9a2e8107c87fdbf74cc2f09ae5eeafbb13ad55
diff --git a/library/RLCMAC_Templates.ttcn b/library/RLCMAC_Templates.ttcn
index e2abd84..939a814 100644
--- a/library/RLCMAC_Templates.ttcn
+++ b/library/RLCMAC_Templates.ttcn
@@ -329,6 +329,23 @@
 		}
 	}
 
+	template RlcmacUlBlock ts_RLCMAC_DL_ACK_NACK_CHREQ(template uint5_t tfi,
+							   AckNackDescription andesc,
+							   boolean retry := false,
+							   template ChannelReqDescription chreq_desc := c_ChReqDesc_default)
+	modifies ts_RLCMAC_DL_ACK_NACK := {
+		ctrl := {
+			payload := {
+				u := {
+					dl_ack_nack := {
+						chreq_desc_presence := '1'B,
+						chreq_desc := chreq_desc
+					}
+				}
+			}
+		}
+	}
+
 	/* Template for uplink Data block */
 	template RlcmacUlBlock t_RLCMAC_UL_DATA(template uint5_t tfi, template uint4_t cv, template uint7_t bsn,
 						template LlcBlocks blocks := {}, template boolean stall := false) := {