Remove one-line function in test_volumes_actions

In I526f8940c4f29a93f25f896bc4779a771f4c3eb5, _reset_volume_status's
return value is removed and so it becomes a one-line function. Jordan
Pittier points out that "It's better to directly use
admin_volume_client.reset_volume_status() in tests instead of
calling an alias.", so this is to remove the one-line function to
keep code clean.

Change-Id: I89bb06c15a4f2ac9b55f1ee5437f92eb885f05ca
diff --git a/tempest/api/volume/admin/test_volumes_actions.py b/tempest/api/volume/admin/test_volumes_actions.py
index 728a9e6..e7a3f62 100644
--- a/tempest/api/volume/admin/test_volumes_actions.py
+++ b/tempest/api/volume/admin/test_volumes_actions.py
@@ -34,27 +34,26 @@
         # Create a test shared volume for tests
         cls.volume = cls.create_volume()
 
-    def _reset_volume_status(self, volume_id, status):
-        # Reset the volume status
-        self.admin_volume_client.reset_volume_status(volume_id, status=status)
-
     def tearDown(self):
         # Set volume's status to available after test
-        self._reset_volume_status(self.volume['id'], status='available')
+        self.admin_volume_client.reset_volume_status(
+            self.volume['id'], status='available')
         super(VolumesActionsV2Test, self).tearDown()
 
     def _create_reset_and_force_delete_temp_volume(self, status=None):
         # Create volume, reset volume status, and force delete temp volume
         temp_volume = self.create_volume()
         if status:
-            self._reset_volume_status(temp_volume['id'], status)
+            self.admin_volume_client.reset_volume_status(
+                temp_volume['id'], status=status)
         self.admin_volume_client.force_delete_volume(temp_volume['id'])
         self.client.wait_for_resource_deletion(temp_volume['id'])
 
     @test.idempotent_id('d063f96e-a2e0-4f34-8b8a-395c42de1845')
     def test_volume_reset_status(self):
         # test volume reset status : available->error->available
-        self._reset_volume_status(self.volume['id'], 'error')
+        self.admin_volume_client.reset_volume_status(
+            self.volume['id'], status='error')
         volume_get = self.admin_volume_client.show_volume(
             self.volume['id'])['volume']
         self.assertEqual('error', volume_get['status'])