media: imx258: Add imx258 camera sensor driver

Add a V4L2 sub-device driver for the Sony IMX258 image sensor.
This is a camera sensor using the I2C bus for control and the
CSI-2 bus for data.

Signed-off-by: Jason Chen <jasonx.z.chen@intel.com>
Signed-off-by: Andy Yeh <andy.yeh@intel.com>
Signed-off-by: Alan Chiang <alanx.chiang@intel.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>