media: rkisp1: Support the ISP parallel input

The ISP has a parallel input, exposed through port 1 in the device tree
node. While the driver supports configuring the ISP for the parallel and
BT.656 input modes, the DT parsing code, the subdev bound handler and
the ISP stream start handler only support the CSI input. Extend them to
support the parallel input.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Dafna Hirschfeld <dafna@fastmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>