media: imx: imx7-media-csi: Add i.MX8MM identification

The CSI in the i.MX8MM is nearly identical to the one found in the
i.MX7, but minor differences will require specific code paths. Add CSI
model information to the OF match data and store it in the imx7_csi
structure for future use.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>