This patch creates a new header with a potential standard i2c sensor attribute type (which simply includes an int representing the sensor number/index) and the associated macros, SENSOR_DEVICE_ATTR to define a static attribute and to_sensor_dev_attr to get a sensor_device_attribute reference from an embedded device_attribute reference. Signed-off-by: Yani Ioannou <yani.ioannou@gmail.com>