[media] v4l: xilinx: Add Xilinx Video IP core

Xilinx platforms have no hardwired video capture or video processing
interface. Users create capture and memory to memory processing
pipelines in the FPGA fabric to suit their particular needs, by
instantiating video IP cores from a large library.

The Xilinx Video IP core is a framework that models a video pipeline
described in the device tree and expose the pipeline to userspace
through the media controller and V4L2 APIs.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>
Signed-off-by: Radhey Shyam Pandey <radheys@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>