media: Revert "media: dt-bindings: media: Use OF graph schema"

This reverts commit f61eb7bc.

While aligning with the OF graph schema will be done for the media DT
bindings, this patch got merged a little too hastily. Revert it for now.

Suggested-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>