binman: Correct the search patch for pylibfdt

Now that binman uses tools/ as its base directory for importing modules,
the path to the pylibfdt build by U-Boot is incorrect. Fix it with a new
path.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

tools/binman/main.py

@@ -26,6 +26,7 @@ from patman import test_util
 
 # Bring in the libfdt module
 sys.path.insert(2, 'scripts/dtc/pylibfdt')
+sys.path.insert(2, os.path.join(our_path, '../../scripts/dtc/pylibfdt'))
 sys.path.insert(2, os.path.join(our_path,
                 '../../build-sandbox_spl/scripts/dtc/pylibfdt'))