media: stop pretending to maintain cafe and ov7670

It's been a long time since I could credibly claim to be maintaining these
drivers; I'm not even sure my hardware works anymore.  Mark them orphan.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>