mailmap: add entries for Christoph Paasch

mailmap: add entries for Christoph Paasch

Map the email addresses used for previous kernel contributions to the
current OpenAI address. This prevents get_maintainer.pl from listing
historical addresses as patch recipients.

Suggested-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Christoph Paasch <cpaasch@openai.com>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260806-b4-mailman-v1-1-b4d7bc0ffd1c@openai.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>