tools/genboardscfg.py: change shebang into /usr/bin/env python2

This tool only works on python 2 (python 2.6 or lator).

Change the shebang to make sure the script is run by python 2
and clearly say the supported version in the comment block.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Series-cc: sjg
Series-cc: trini
README.kconfig: document backward compatibility "make *_config"

Commit 3ff291f3 added "<board>_config" target for backward
compatibility.  It should be documented.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Series-cc: trini
Series-cc: sjg
Series-cc: Jeroen Hofstee <jeroen@myspectrum.nl>
Series-cc: Stephen Warren <swarren@nvidia.com>
tools: moveconfig.py
Do not send: Kconfiglib

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
moveconfig2
Fast genboardscfg.py

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>