media: MAINTAINERS: drop unreachable contact for MEDIATEK JPEG DRIVER

After sending a patch to Rick Chang, the mediatek mail server responded:

  ** Message not delivered **

  Your message couldn't be delivered to rick.chang@mediatek.com because
  the remote server is misconfigured. See technical details below for more
  information.

  The response from the remote server was:
  550 Relaying mail to rick.chang@mediatek.com is not allowed

So, drop Rick Chang from the MEDIATEK JPEG DRIVER section.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>