media: rockchip: rkcif: add abstraction for interface and crop blocks

media: rockchip: rkcif: add abstraction for interface and crop blocks

Add an abstraction for the INTERFACE and CROP parts of the different
Rockchip Camera Interface (CIF) variants. These parts are represented
as V4L2 subdevice with one sink pad and one source pad. The sink pad
is connected to a subdevice: either the subdevice provided by the
driver of the companion chip connected to the DVP, or the subdevice
provided by the MIPI CSI-2 receiver. The source pad is connected to
V4l2 device(s) provided by one or many instance(s) of the DMA
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>