mailmap: update entries for Stephen Hemminger

Map all my old email addresses to current address.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Link: https://lore.kernel.org/r/20230306194405.108236-1-stephen@networkplumber.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>