V4L/DVB (12187): uvcvideo: Move UVC definitions to linux/usb/video.h

To make UVC constants accessible by a future UVC gadget driver, move them from
drivers/media/video/uvc/uvcvideo.h to include/linux/usb/video.h.

Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>