Added Kamstrup Multical 40x component (#4200)

Co-authored-by: Chris Feenstra <chris@cfeenstra.nl>
Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
Co-authored-by: cfeenstra1024 <git@cfeenstra.nl>

esphome/components/ezo_pmp/__init__.py

@@ -1,7 +1,13 @@
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome.components import i2c
-from esphome.const import CONF_ADDRESS, CONF_COMMAND, CONF_ID, CONF_DURATION
+from esphome.const import (
+    CONF_ADDRESS,
+    CONF_COMMAND,
+    CONF_ID,
+    CONF_DURATION,
+    CONF_VOLUME,
+)
 from esphome import automation
 from esphome.automation import maybe_simple_id
 
@@ -9,7 +15,6 @@ CODEOWNERS = ["@carlos-sarmiento"]
 DEPENDENCIES = ["i2c"]
 MULTI_CONF = True
 
-CONF_VOLUME = "volume"
 CONF_VOLUME_PER_MINUTE = "volume_per_minute"
 
 ezo_pmp_ns = cg.esphome_ns.namespace("ezo_pmp")