media: i2c: Add support for the OV8865 image sensor

The OV8865 is a 8 Mpx CMOS image sensor producing 3264x2448 at 30 fps.
Other modes (including some with sub-sampling) are available too.
It outputs 10-bit bayer CFA data through a MIPI CSI-2 interface with
up to 4 lanes supported.

Some register initialisation sequences are still needed for this driver,
as they cover registers for which no documentation is available.

This work is based on the first version of the driver submitted by
Kévin L'hôpital, which was adapted to mainline from the Allwinner BSP.
This version is a rewrite of the first version that matches the structure
of the OV5648 driver, with explicit PLL configuration, all the necessary
mode-specific fields, associatied registers and reduced static sequences.

It was tested with the Banana Pi Camera Board v3 and the Banana Pi M3.

Co-developed-by: Kévin L'hôpital <kevin.lhopital@bootlin.com>
Signed-off-by: Kévin L'hôpital <kevin.lhopital@bootlin.com>
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>