patman: Convert camel case in tools.py

Convert this file to snake case and update all files which use it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/func_test.py b/tools/patman/func_test.py
index 9f4e03e..defa1cc 100644
--- a/tools/patman/func_test.py
+++ b/tools/patman/func_test.py
@@ -338,7 +338,7 @@
             text (str): Text to put into the file
         """
         path = os.path.join(self.gitdir, fname)
-        tools.WriteFile(path, text, binary=False)
+        tools.write_file(path, text, binary=False)
         index = self.repo.index
         index.add(fname)
         author = pygit2.Signature('Test user', 'test@email.com')