binman: Correct some import statements

Some of these were not converted when binman moved to use absolute paths.
Fix them.

Also drop the import of 'test' which is a directory, not a module.

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

tools/binman/main.py

@@ -61,7 +61,6 @@ def RunTests(debug, verbosity, processes, test_preserve_dirs, args, toolpath):
     from binman import fdt_test
     from binman import ftest
     from binman import image_test
-    from binman import test
     import doctest
 
     result = unittest.TestResult()