Cleanup using about the data_utils module and functions

 HACKING officially discourages symbol import directly because it makes
it harder to track down that a function was imported. Recently, we keep
this rule but there are many code that don't keep it.
 This commit cleanups them.

Change-Id: Ibda1a5e424280bad8535ee27f66dec99bf68f676
diff --git a/tempest/api/volume/test_volumes_get.py b/tempest/api/volume/test_volumes_get.py
index f2915f7..14120fe 100644
--- a/tempest/api/volume/test_volumes_get.py
+++ b/tempest/api/volume/test_volumes_get.py
@@ -16,7 +16,7 @@
 #    under the License.
 
 from tempest.api.volume import base
-from tempest.common.utils.data_utils import rand_name
+from tempest.common.utils import data_utils
 from tempest.test import attr
 from tempest.test import services
 
@@ -46,7 +46,7 @@
     def _volume_create_get_update_delete(self, **kwargs):
         # Create a volume, Get it's details and Delete the volume
         volume = {}
-        v_name = rand_name('Volume')
+        v_name = data_utils.rand_name('Volume')
         metadata = {'Type': 'Test'}
         # Create a volume
         resp, volume = self.client.create_volume(size=1,
@@ -88,7 +88,7 @@
             self.assertEqual(boot_flag, False)
 
         # Update Volume
-        new_v_name = rand_name('new-Volume')
+        new_v_name = data_utils.rand_name('new-Volume')
         new_desc = 'This is the new description of volume'
         resp, update_volume = \
             self.client.update_volume(volume['id'],
@@ -118,7 +118,7 @@
     def test_volume_get_metadata_none(self):
         # Create a volume without passing metadata, get details, and delete
         volume = {}
-        v_name = rand_name('Volume-')
+        v_name = data_utils.rand_name('Volume-')
         # Create a volume without metadata
         resp, volume = self.client.create_volume(size=1,
                                                  display_name=v_name,