mailmap: update Alex Hung's email address

I am no longer at Canonical and add entry of my personal email address.

Link: https://lkml.kernel.org/r/20221114001302.671897-1-alex.hung@amd.com


Signed-off-by: Alex Hung <alexhung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>