libcamera: camera_sensor: Break out properties initialization

Break out initialization to its own function in preparation to
add more properties.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

include/libcamera/internal/camera_sensor.h

@@ -69,6 +69,7 @@ protected:
 
 private:
 	int generateId();
+	int initProperties();
 
 	const MediaEntity *entity_;
 	std::unique_ptr<V4L2Subdevice> subdev_;