[media] v4l: vsp1: Add DT support

Implement support for the VSP1 DT bindings in the VSP1 driver. The
driver now first retrieves platform data either from the platform data
pointer or by reading the device tree node, and then validates it
regardless of the platform data source.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>