BTS_Tests: do L1CTL.clear in f_pcu_to_l1()

When calling f_pcu_to_l1(), the L1CTL port still contains many BCCH
related L1CTL DATA.ind messages in the queue.  It's not a really a
problem since they all get discarded, but still they're producing
lots of useless TTCN_MATCHING log messages.

Change-Id: I57b745bcfc48dc621359658cd43d2ee622fde49b
---
M bts/BTS_Tests.ttcn
1 file changed, 15 insertions(+), 0 deletions(-)

diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index d901664..9d7ab65 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -5564,6 +5564,7 @@
 	timer T := 5.0;
 	var L1ctlMessage rx_dl;
 
+	L1CTL.clear;
 	PCU.clear;
 	if (wait_rts) {
 		f_pcu_wait_rts_and_data_req(bts_nr, trx_nr, ts_nr, sapi, data);

