libcamera: camera_sensor: Add accessors for sensor ID

Add an accessors so that the sensor ID can be used outside CameraSensor.

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

src/libcamera/camera_sensor.cpp

@@ -290,6 +290,16 @@ int CameraSensor::init()
  * \return The sensor model name
  */
 
+/**
+ * \fn CameraSensor::id()
+ * \brief Retrieve the sensor ID
+ *
+ * The sensor ID is a free-form string that uniquely identifies the sensor in
+ * the system. The ID satisfies the requirements to be used as a camera ID.
+ *
+ * \return The sensor ID
+ */
+
 /**
  * \fn CameraSensor::entity()
  * \brief Retrieve the sensor media entity