35fec487e30f05c81bd135326a993dad7f861812 fixed opkg usage,
but when using buildroot we were still defaulting to
ip(6)tables-legacy
Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>
(cherry picked from commit 0c8d7e34ab35f6b41f034fd94fec740970e0125b)