[media] v4l: xilinx: Add Test Pattern Generator driver

The TPG generates multiple static or dynamic test patterns. The driver
currently hardcodes the pattern to the moving box pattern.

Signed-off-by: Christian Kohn <christian.kohn@xilinx.com>
Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.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>