[media] media: rcar_vin: Use correct pad number in try_fmt

Fix rcar_vin_try_fmt's use of an inappropriate pad number when calling
the subdev set_fmt function - for the ADV7612, IDs should be non-zero.

Signed-off-by: William Towle <william.towle@codethink.co.uk>
Reviewed-by: Rob Taylor <rob.taylor@codethink.co.uk>
[ulrich.hecht+renesas@gmail.com: adapted to rcar-vin rewrite]
Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>