[media] ezkit/cobalt: drop unused op_656_range setting

The adv7604/adv7842 drivers now handle that register setting themselves
and need no input from platform data anymore.

This was a left-over from the time that the pixelport output format was
decided by the platform data.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Scott Jiang <scott.jiang.linux@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>