Removing wrapper method for "wait_for_volume_status" function

The wait_for_volume_status method in the base_volumes_client.py file is
a wrapper method that just uses the waiters.wait_for_volume_status function.
The wait_for_volume_status method is not a service method and that is why
it should be removed and the waiters.wait_for_volume_status function should
be used instead.

Partially implements blueprint consistent-service-method-names

Change-Id: I4516a2cc2dd6ada8d0a49392a98b949edc09a9fd
diff --git a/tempest/scenario/test_stamp_pattern.py b/tempest/scenario/test_stamp_pattern.py
index 6121a90..16352c6 100644
--- a/tempest/scenario/test_stamp_pattern.py
+++ b/tempest/scenario/test_stamp_pattern.py
@@ -19,6 +19,7 @@
 import testtools
 
 from tempest.common.utils import data_utils
+from tempest.common import waiters
 from tempest import config
 from tempest import exceptions
 from tempest.lib import decorators
@@ -72,7 +73,8 @@
             except lib_exc.NotFound:
                 pass
         self.addCleanup(cleaner)
-        self.volumes_client.wait_for_volume_status(volume['id'], 'available')
+        waiters.wait_for_volume_status(self.volumes_client,
+                                       volume['id'], 'available')
         self.snapshots_client.wait_for_snapshot_status(snapshot['id'],
                                                        'available')
         self.assertEqual(snapshot_name, snapshot['display_name'])