media: ov2680: Stop sending more data then requested

There is no reason to send OV2680_END_MARGIN extra columns on top of
the mode width and the same for sending extra lines over the mode height.

This sending of extra lines/columns was inherited from the atomisp
ov2680 driver, it is unclear why this was done and this complicates
adding V4L2_CID_VBLANK support, so remove it.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>