media: i2c: imx258: add support for binding via device tree

The IMX258 can be used also on embedded designs using device tree so
allow the sensor to bind to a device tree node.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>