MAINTAINERS: Adjust Dell drivers to email alias

A team of engineers will be helping to service these drivers in
the future rather than just one person.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Link: https://lore.kernel.org/r/20210401162206.26901-2-mario.limonciello@dell.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>