mailmap: redirect inactive address <ao2@amarulasolutions.com>

The email address <ao2@amarulasolutions.com> is not active anymore, use
Antonio's personal email address <ao2@ao2.it> in case someone wants to
get in touch for the code wrote for Amarula Solutions.

Signed-off-by: Antonio Ospite <ao2@ao2.it>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>