media: rcar-vin: Remove emulated SEQ_{TB,BT}

media: rcar-vin: Remove emulated SEQ_{TB,BT}

When the driver was converted from soc_camera software support for
V4L2_FIELD_SEQ_TB and V4L2_FIELD_SEQ_BT were added. This was done by
capturing twice to the same VB2 buffer, but at different offsets.

This turned out to be a bad idea and it never really worked properly in
all situations. As the hardware can't support this mode natively remove
trying to emulate it in software. It's still possible to capture TOP or
BOTTOM fields separately or both ALTERNATING. If user-space wants the
same  fields in the same buffer the same hack to capture twice to the
same buffer can be done.

Removing this error prone emulated support pave ways in future work to
simplify the internal buffer handling and making it less fragile, while
enabling adding support for other features the hardware actually
supports.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Tested-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>