Add some constants back that were used to Flexit and Stiebel (#98042)

* Add some constants back that were used

* Update __init__.py

---------

Co-authored-by: Erik Montnemery <erik@montnemery.com>

homeassistant/components/flexit/climate.py

@@ -16,8 +16,6 @@ from homeassistant.components.climate import (
 from homeassistant.components.modbus import (
     CALL_TYPE_REGISTER_HOLDING,
     CALL_TYPE_REGISTER_INPUT,
-    CALL_TYPE_WRITE_REGISTER,
-    CONF_HUB,
     DEFAULT_HUB,
     ModbusHub,
     get_hub,
@@ -34,6 +32,9 @@ import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
 
+CALL_TYPE_WRITE_REGISTER = "write_register"
+CONF_HUB = "hub"
+
 PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
     {
         vol.Optional(CONF_HUB, default=DEFAULT_HUB): cv.string,