media: dt-bindings: media: Add bindings for imx412

- Add dt-bindings documentation for Sony imx412 sensor driver
- Add MAINTAINERS entry for Sony imx412 binding documentation

Signed-off-by: Martina Krasteva <martinax.krasteva@intel.com>
Acked-by: Daniele Alessandrelli <daniele.alessandrelli@intel.com>
Acked-by: Paul J. Murphy <paul.j.murphy@intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>