legacy: add missing option for util-linux' wdctl

In 349c9c7f (package/util-linux: add more tool select options), the
util-linux' wdctl option was renamed, but a entry in the legacy menu was
no added.

Add this now.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Maxim Mikityanskiy <maxtram95@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>