media: dt-bindings: media: document the nxp,imx8mq-mipi-csi2 receiver phy and controller

The i.MX8MQ SoC integrates a different MIPI CSI receiver as the i.MX8MM so
describe the DT bindings for it.

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>