media: rcar-vin: Drop min_queued_buffers

media: rcar-vin: Drop min_queued_buffers

The R-Car VIN driver already uses a scratch buffer to sustain capture
operations in absence of a frame buffer provided by userspace.

There is no reason to require 4 buffers queued at all times for the
driver to operate. Drop min_queued_buffers from the VIN driver to allow
single-frame capture operations.

Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Reviewed-by: Jai Luthra <jai.luthra+renesas@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>