media: rcar-isp: Add Renesas R-Car Image Signal Processor driver

Add a V4L2 driver for Renesas R-Car Image Signal Processor. The driver
supports the R-Car V3U SoC where the ISP IP sits between the R-Car CSI-2
receiver and VIN and filters the CSI-2 data based on VC/DT and directs
the video stream to different VIN IPs.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>