media: ti: j721e-csi2rx: add support for processing virtual channels

media: ti: j721e-csi2rx: add support for processing virtual channels

Use get_frame_desc() to get the frame desc from the connected source,
and use the provided virtual channel and DT instead of defaults.

As we don't support multiple streams yet, we will just always use
stream 0. If the source doesn't support get_frame_desc(), fall back
to the previous method of always capturing virtual channel 0.

Reviewed-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
Co-developed-by: Pratyush Yadav <p.yadav@ti.com>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
Signed-off-by: Jai Luthra <j-luthra@ti.com>
Signed-off-by: Rishikesh Donadkar <r-donadkar@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>