media: rockchip: rkcif: add abstraction for dma blocks

media: rockchip: rkcif: add abstraction for dma blocks

Add an abstraction for the DMA parts and the ping-pong scheme (a
double-buffering mechanism) of the different CIF variants. Each
stream is represented as V4L2 device whose corresponding media
entity has one sink pad. This sink pad is connected to an instance
of the INTERFACE/CROP abstraction.

Tested-by: Gerald Loacker <gerald.loacker@wolfvision.net>
Reviewed-by: Gerald Loacker <gerald.loacker@wolfvision.net>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Mehdi Djait <mehdi.djait@linux.intel.com>
Signed-off-by: Michael Riesch <michael.riesch@collabora.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
[hverkuil: dropped deprecated vb2_ops_wait_prepare/finish callbacks]