patman: Drop references to __future__

We don't need these now that the tools using Python 3. Drop them.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/cbfs_util_test.py

@@ -9,8 +9,6 @@ These create and read various CBFSs and compare the results with expected
 values and with cbfstool
 """
 
-from __future__ import print_function
-
 import io
 import os
 import shutil