host-tools: use python2 explicitly for shebang

All of these host tools are apparently written for Python2,
not Python3.

Use 'python2' in the shebang line according to PEP 394
(https://www.python.org/dev/peps/pep-0394/).

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

scripts/dtc/pylibfdt/setup.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 
 """
 setup.py file for SWIG libfdt