Move site_backchannel and site_tpm module into client/cros dir.

client/site_tests/network_3GStressEnable/network_3GStressEnable.py

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-from autotest_lib.client.bin import site_backchannel, test, utils
+from autotest_lib.client.bin import test, utils
 from autotest_lib.client.common_lib import error
 
 import logging, re, socket, string, time, urllib2
 import dbus, dbus.mainloop.glib, gobject
 
 from autotest_lib.client.cros import flimflam_test_path
 import flimflam, mm
 
 class network_3GStressEnable(test.test):
     version = 1
@@ skipping 20 matching lines @@
     def run_once(self, name='usb', cycles=10, min=1, max=20):
         flim = flimflam.FlimFlam(dbus.SystemBus())
         device = flim.FindElementByNameSubstring('Device', name)
         if device is None:
             device = flim.FindElementByPropertySubstring('Device', 'Interface',
                                                          name)
         self.SetPowered(device, 0)
         for t in xrange(max, min, -1):
             for _ in xrange(cycles):
                 self.test(device, t / 10.0)