pylint: Ignore usage of 'unicode' before assignment

New versions of pylint ignore Python 2 functions and types, evaluating
'unicode' as "undefined". ansible-freeipa will always define 'unicode'
when running under Python 3, and it is always defined under Python 2.

This patch fixes these false positives.

plugins/modules/iparole.py

@@ -293,7 +293,7 @@ def result_get_value_lowercase(res_find, key, default=None):
     if existing is not None:
         if isinstance(existing, (list, tuple)):
             existing = [to_text(item).lower() for item in existing]
-        if isinstance(existing, (str, unicode)):
+        if isinstance(existing, (str, unicode)):  # pylint: disable=E0606
             existing = existing.lower()
     else:
         existing = default