mailmap: Add entry for Andrew Donnellan

I'm leaving IBM in January 2026. Add mailmap aliases to switch to using my
personal email for now.

(I will send a patch to update MAINTAINERS soon, hopefully after I can get
someone to replace me.)

Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20251208-mailmap-v1-1-524d5b9d175b@linux.ibm.com

Author: ajdlinux

.mailmap

@@ -75,6 +75,9 @@ Andreas Herrmann <aherrman@de.ibm.com>
 Andreas Hindborg <a.hindborg@kernel.org> <a.hindborg@samsung.com>
 Andrej Shadura <andrew.shadura@collabora.co.uk>
 Andrej Shadura <andrew@shadura.me> <andrew@beldisplaytech.com>
+Andrew Donnellan <andrew+kernel@donnellan.id.au> <andrew@donnellan.id.au>
+Andrew Donnellan <andrew+kernel@donnellan.id.au> <ajd@linux.ibm.com>
+Andrew Donnellan <andrew+kernel@donnellan.id.au> <andrew.donnellan@au1.ibm.com>
 Andrew Morton <akpm@linux-foundation.org>
 Andrew Murray <amurray@thegoodpenguin.co.uk> <amurray@embedded-bits.co.uk>
 Andrew Murray <amurray@thegoodpenguin.co.uk> <andrew.murray@arm.com>