Clean up bare raised pylint warning

Clean up bare raises warning by linter, pylint
complains about raising an exception specified
and not in the context of an exception handler.
Added an exception.

Change-Id: I1d77c6ab9849510c45fdd99dd57b71bde9a57da6
Signed-off-by: Chuck Short <chucks@redhat.com>

.pylintrc

@@ -80,7 +80,6 @@ disable=
  keyword-arg-before-vararg,
  too-many-function-args,
  unsupported-assignment-operation,
- misplaced-bare-raise,
  not-an-iterable,
  unsupported-membership-test,
  unsupported-assignment-operation,

cinder/volume/drivers/huawei/rest_client.py

@@ -2374,7 +2374,7 @@ class RestClient(object):
         result = self.call(url, None, "GET", log_filter_flag=True)
 
         if result['error']['code'] != 0:
-            raise
+            raise Exception(_('Failed to get object count.'))
 
         if result.get("data"):
             return result.get("data").get("COUNT")

cinder/volume/drivers/netapp/dataontap/client/api.py

@@ -348,7 +348,7 @@ class NaElement(object):
         if isinstance(na_element, NaElement):
             self._element.append(na_element._element)
             return
-        raise
+        raise Exception(_('Failed to add child element.'))
 
     def get_child_by_name(self, name):
         """Get the child element by the tag name."""