MAINTAINERS: mailmap: add entries for Antonio Quartulli

Update MAINTAINERS and link my various emails to
my company email address in .mailmap.

Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>