patman: Don't return the series in FixPatches()

There is no need for this function to return the same object that was
passed in. Drop the return value.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

tools/patman/patchstream.py

@@ -477,7 +477,6 @@ def FixPatches(series, fnames):
             print
         count += 1
     print('Cleaned %d patches' % count)
-    return series
 
 def InsertCoverLetter(fname, series, count):
     """Inserts a cover letter with the required info into patch 0

tools/patman/patman.py

@@ -141,8 +141,8 @@ else:
                 series)
 
     # Fix up the patch files to our liking, and insert the cover letter
-    series = patchstream.FixPatches(series, args)
-    if series and cover_fname and series.get('cover'):
+    patchstream.FixPatches(series, args)
+    if cover_fname and series.get('cover'):
         patchstream.InsertCoverLetter(cover_fname, series, options.count)
 
     # Do a few checks on the series