Rename test module to testenv and update references

Preparation to move current Test class into its own module test from
suite module.

Change-Id: I520bd046cb09042b5567d967f951f050e4e02e85
diff --git a/suites/voice/mo_mt_call.py b/suites/voice/mo_mt_call.py
index 8cd3b23..b2d6f8d 100755
--- a/suites/voice/mo_mt_call.py
+++ b/suites/voice/mo_mt_call.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-from osmo_gsm_tester.test import *
+from osmo_gsm_tester.testenv import *
 
 hlr = suite.hlr()
 bts = suite.bts()