dt-bindings: media: i2c: Add IMX296 CMOS sensor binding

Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
add MAINTAINERS entry for the binding and driver.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rob Herring <robh@kernel.org>