BTS_Tests: use f_PCUIF_tx_mac_block_agch in TC_pcu_data_req_agch

The testcase TC_pcu_data_req_agch uses SAPI PCU_IF_SAPI_AGCH. Since we
now have a function f_PCUIF_tx_mac_block_agch() to send MAC blocks over
the AGCH using the recently introduced SAPI PCU_IF_SAPI_AGCH_2, lets use
this function instead.

Related: OS#5927
Change-Id: I341bbd01e8132fab913d307bfb4b2fb873cdde3c
diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index 6109159..317ed70 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -5792,7 +5792,8 @@
 	f_l1_tune(L1CTL);
 
 	f_TC_pcu_act_req(0, 0, 7, true);
-	f_pcu_data_req(0, 0, 0, 0, 0, PCU_IF_SAPI_AGCH, c_PCU_DATA);
+	f_PCUIF_tx_mac_block_agch(PCU, g_pcu_conn_id, c_PCU_DATA, confirm := false,
+				  wait_for_cnf := false, msg_id := 'ffffffff'O);
 
 	T.start;
 	alt {