media: imx: imx7-media-csi: Use dual sampling for YUV 1X16

The CSI bridge should operate in dual components mode when it is
connected to a pixel transmitter that transfers two components at a time
in YUV 422 formats (16 bits, Y + U/V).

Use the image format variants to determine if single or dual component mode
should be used.

Add a note to the TODO file to record that the list of supported formats
should be restricted to the SoC model the CSI bridge is integrated on
to avoid potential pipeline mis-configurations.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Rui Miguel Silva <rmfrfs@gmail.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>