patman: Correct pylint errors

Fix pylint errors that can be fixed and mask those that seem to be
incorrect.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/series.py b/tools/patman/series.py
index 891f278..3075378 100644
--- a/tools/patman/series.py
+++ b/tools/patman/series.py
@@ -122,8 +122,7 @@
             cc_list = list(self._generated_cc[commit.patch])
             for email in sorted(set(cc_list) - to_set - cc_set):
                 if email == None:
-                    email = col.build(col.YELLOW, "<alias '%s' not found>"
-                            % tag)
+                    email = col.build(col.YELLOW, '<alias not found>')
                 if email:
                     print('      Cc: ', email)
         print