media: cxusb: add raw mode support for Medion MD95700

This adds raw (unprocessed) BT.656 stream capturing support for the analog
part of Medion 95700.
It can be enabled by setting CXUSB_EXTENDEDMODE_CAPTURE_RAW flag in
parm.capture.extendedmode passed to VIDIOC_S_PARM.

Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>