media: ov2680: Drop hts, vts ov2680_mode struct members

The hts, vts ov2680_mode struct members always contain
OV2680_PIXELS_PER_LINE resp. OV2680_LINES_PER_FRAME,
drop them and simply use these values directly.

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>