Switch to use new base_client.BaseClient

Class 'tempest.lib.services.volume.v3.base_client.BaseClient' has moved
to 'tempest.lib.services.volume.base_client.BaseClient' in version Pike
[1] and will be removed in a future version.

[1] I645ae35daebd924c4c4523163e5419cc050bb0ed

Change-Id: I4bcc9e2c7b6fd0096dc9c8f679ef680ea0d7bbbf
diff --git a/cinder/tests/tempest/services/volume_revert_client.py b/cinder/tests/tempest/services/volume_revert_client.py
index 285494a..0d54701 100644
--- a/cinder/tests/tempest/services/volume_revert_client.py
+++ b/cinder/tests/tempest/services/volume_revert_client.py
@@ -15,7 +15,7 @@
 
 from oslo_serialization import jsonutils as json
 from tempest.lib.common import rest_client
-from tempest.lib.services.volume.v3 import base_client
+from tempest.lib.services.volume import base_client
 
 
 class VolumeRevertClient(base_client.BaseClient):