doc:it_IT: remove unreferenced and not translated page

The netdev-FAQ page in the italian translation was creted to avoid
having broken links. With the evolution of the documentation this was
not referenced anymore, but the page never removed.

Reported-by: Davide Benini <davide.benini@gmail.com>
Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240209222115.31505-1-federico.vaga@vaga.pv.it