media: dt-bindings: media: document SK Hynix Hi-846 MIPI CSI-2 8M pixel sensor

Document the bindings used for the SK Hynix Hi-846 CMOS camera driver.

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.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>