patman: fix series-notes handling for buildman

A patman series with a 'Series-notes' section causes
buildman to crash with:

    self.series.notes += self.section
    TypeError: cannot concatenate 'str' and 'list' objects

Fix by initializing series.notes as a one-element array
rather than a scalar.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

tools/patman/series.py

@@ -69,7 +69,10 @@ class Series(dict):
 
         # Otherwise just set the value
         elif name in valid_series:
-            self[name] = value
+            if name=="notes":
+                self[name] = [value]
+            else:
+                self[name] = value
         else:
             raise ValueError("In %s: line '%s': Unknown 'Series-%s': valid "
                         "options are %s" % (commit.hash, line, name,