tests: Replace 'suite' with 'tenv'

Change-Id: I777ec59ffd83b861ddc09e85e52d7a8896264b8c
diff --git a/sysmocom/suites/gprs/iperf3m4.py b/sysmocom/suites/gprs/iperf3m4.py
index 1cc27ed..713757c 100755
--- a/sysmocom/suites/gprs/iperf3m4.py
+++ b/sysmocom/suites/gprs/iperf3m4.py
@@ -2,7 +2,7 @@
 from osmo_gsm_tester.testenv import *
 
 import testlib
-suite.test_import_modules_register_for_cleanup(testlib)
+tenv.test_import_modules_register_for_cleanup(testlib)
 from testlib import setup_run_iperf3_test_parallel
 
 setup_run_iperf3_test_parallel(4)