arm64: dts: imx8mp: Add DT nodes for the two ISPs

The ISP supports both CSI and parallel interfaces, where port 0
corresponds to the former and port 1 corresponds to the latter. Since
the i.MX8MP's ISPs are connected by the parallel interface to the CSI
receiver, set them both to port 1.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>