mailmap: add John Crispin's entry

mailmap: add John Crispin's entry

John has not been CCed on some of the fixes which perhaps resulted
in the lack of review tags:

Subsystem MEDIATEK ETHERNET DRIVER
  Changes 50 / 295 (16%)
  Last activity: 2023-01-17
  Felix Fietkau <nbd@nbd.name>:
    Author 8bd8dcc5e47f 2022-11-18 00:00:00 33
    Tags 8bd8dcc5e47f 2022-11-18 00:00:00 38
  John Crispin <john@phrozen.org>:
  Sean Wang <sean.wang@mediatek.com>:
    Author 880c2d4b2fdf 2019-06-03 00:00:00 7
    Tags a5d75538295b 2020-04-07 00:00:00 10
  Mark Lee <Mark-MC.Lee@mediatek.com>:
    Author 8d66a8183d0c 2019-11-14 00:00:00 4
    Tags 8d66a8183d0c 2019-11-14 00:00:00 4
  Lorenzo Bianconi <lorenzo@kernel.org>:
    Author 08a764a7c51b 2023-01-17 00:00:00 68
    Tags 08a764a7c51b 2023-01-17 00:00:00 74
  Top reviewers:
    [12]: leonro@nvidia.com
    [6]: f.fainelli@gmail.com
    [6]: andrew@lunn.ch
  INACTIVE MAINTAINER John Crispin <john@phrozen.org>

map his old address to the up to date one.

Acked-by: John Crispin <john@phrozen.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>