mailmap: add linux.dev alias for Brendan Higgins

Because of my new work remote setup at Google, I can no longer use command
line tools with my google.com email address, for this reason I got a
linux.dev account.  So update the mailmap to show the new alias I will be
using.

Link: https://lkml.kernel.org/r/20220725215833.789133-1-brendan.higgins@linux.dev


Signed-off-by: Brendan Higgins <brendan.higgins@linux.dev>
Reviewed-by: David Gow <davidgow@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>