iperf3: Support configuring data direction (dl vs ul)

Change-Id: I6b5b740beac22015c952ce826c034031ad4c4465
diff --git a/suites/gprs/lib/testlib.py b/suites/gprs/lib/testlib.py
index 284ca63..c0af372 100644
--- a/suites/gprs/lib/testlib.py
+++ b/suites/gprs/lib/testlib.py
@@ -16,7 +16,7 @@
     procs = []
     for i in range(len(iperf3clients)):
         print("Running iperf3 client to %s through %r" % (str(iperf3clients[i]), repr(ms_li[i].tmp_ctx_id)))
-        procs.append(iperf3clients[i].prepare_test_proc(ms_li[i].netns()))
+        procs.append(iperf3clients[i].prepare_test_proc(False, ms_li[i].netns()))
     try:
         for proc in procs:
             proc.launch()