checkpatch: Fix personal word list storage.

The enchant dictionary synchronizes additions to the source file.
Keep the two word source separate by adding the extra words only
to the current session.

Fixes: 999c777 ("checkpatch: add a comment spell-checker")
Signed-off-by: Gaetan Rivet <gaetanr@nvidia.com>
Acked-by: Roi Dayan <roid@nvidia.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Aaron Conole <aconole@redhat.com>

utilities/checkpatch.py

@@ -93,7 +93,7 @@ def open_spell_check_dict():
         global spell_check_dict
         spell_check_dict = enchant.Dict("en_US")
         for kw in extra_keywords:
-            spell_check_dict.add(kw)
+            spell_check_dict.add_to_session(kw)
 
         return True
     except: