* Reuse HA constants for serial configuration.
Reusing HA consts reduces the need for translation.
Sort/group constants in const.
* Change const name ATTR_* to CONF_*
* Correct wrong import
* ATTR_* for service and CONF_* for schemas.
* Revert change to service call.
* Rename CONF_TEMPERATURE -> ATTR_TEMPERATURE
Avoid possible division problem in set_temperature.