mailmap: add entry for myself

I no longer work at Savoir-faire Linux but even though MAINTAINERS is
up-to-date, some emails are still sent to my old email address.

Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>