patman: Rename functions in patchstream

Rename these functions to lower case as per PEP8.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/control.py b/tools/buildman/control.py
index b81ecf6..fe874b8 100644
--- a/tools/buildman/control.py
+++ b/tools/buildman/control.py
@@ -276,14 +276,14 @@
                                                       options.branch)
             upstream_commit = gitutil.GetUpstream(options.git_dir,
                                                   options.branch)
-            series = patchstream.GetMetaDataForList(upstream_commit,
+            series = patchstream.get_metadata_for_list(upstream_commit,
                 options.git_dir, 1, series=None, allow_overwrite=True)
 
-            series = patchstream.GetMetaDataForList(range_expr,
+            series = patchstream.get_metadata_for_list(range_expr,
                     options.git_dir, None, series, allow_overwrite=True)
         else:
             # Honour the count
-            series = patchstream.GetMetaDataForList(options.branch,
+            series = patchstream.get_metadata_for_list(options.branch,
                     options.git_dir, count, series=None, allow_overwrite=True)
     else:
         series = None