genboardscfg.py: drop python version comment
genboardscfg.py requires python 3.x since commit 3bc14098d8fb
("genboardscfg.py: Convert to Python 3").
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>