media: cedrus: Remove dst_bufs from context

This array is just duplicated capture buffer queue. Remove it and adjust
code to look into capture buffer queue instead.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>