media: uvcvideo: Report V4L2 device caps through the video_device structure

The V4L2 core populates the struct v4l2_capability device_caps field
from the same field in video_device. There's no need to handle that
manually in the driver.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
Tested-by: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>