Sensor device classes (#14282)

* Added light device class, moved device classes to const

* Removed unnecessary icons

* Replace 'lux' with 'lx'

* Fix comment

* Changed device_class name

homeassistant/components/sensor/linux_battery.py

@@ -10,7 +10,7 @@ import os
 import voluptuous as vol
 
 from homeassistant.components.sensor import PLATFORM_SCHEMA
-from homeassistant.const import CONF_NAME
+from homeassistant.const import CONF_NAME, DEVICE_CLASS_BATTERY
 from homeassistant.helpers.entity import Entity
 import homeassistant.helpers.config_validation as cv
 
@@ -48,8 +48,6 @@ DEFAULT_SYSTEM = 'linux'
 
 SYSTEMS = ['android', 'linux']
 
-ICON = 'mdi:battery'
-
 PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
     vol.Optional(CONF_BATTERY, default=DEFAULT_BATTERY): cv.positive_int,
     vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
@@ -97,7 +95,7 @@ class LinuxBatterySensor(Entity):
     @property
     def device_class(self):
         """Return the device class of the sensor."""
-        return 'battery'
+        return DEVICE_CLASS_BATTERY
 
     @property
     def state(self):
@@ -109,11 +107,6 @@ class LinuxBatterySensor(Entity):
         """Return the unit the value is expressed in."""
         return self._unit_of_measurement
 
-    @property
-    def icon(self):
-        """Return the icon to use in the frontend, if any."""
-        return ICON
-
     @property
     def device_state_attributes(self):
         """Return the state attributes of the sensor."""