The Color Matching Descriptor has been present in USB cameras since
the original version of UVC, but it has never been fully exposed
in Linux.

This change informs V4L2 of all of the UVC colorspace parameters:
color primaries, transfer characteristics, and YCbCr encoding.
videodev2.h doesn't have values for all the possible UVC color settings,
so it is mapped as closely as possible.
Signed-off-by: Adam Goode <agoode@google.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>