usb: gadget: uvc: Add struct for color matching in configs

usb: gadget: uvc: Add struct for color matching in configs

Color matching descriptors are meant to be a per-format piece of data
and we need to be able to support different descriptors for different
formats. As a preliminary step towards that goal, switch the default
color matching configfs functionality to point to an instance of a
new struct uvcg_color_matching. Use the same default values for its
attributes as the currently hard-coded ones so that the interface to
userspace is consistent.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Link: https://lore.kernel.org/r/20230202114142.300858-3-dan.scally@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>