Updated ISY component to not overwrite state_attributes.

The ISY component included an ISYDevice base class that is used by all
of the isy994 platforms. This still overwrote the state_attributes
property instead of the more appropriate device_state_attributes
property. This was also repeated in the isy994 light platform. Both of
these were addressed. This also fixes issue #5428.

homeassistant/components/isy994.py

@@ -272,7 +272,7 @@ def value(self) -> object:
         return self._node.status._val
 
     @property
-    def state_attributes(self) -> Dict:
+    def device_state_attributes(self) -> Dict:
         """Get the state attributes for the device."""
         attr = {}
         if hasattr(self._node, 'aux_properties'):

homeassistant/components/light/isy994.py

@@ -70,7 +70,7 @@ def turn_on(self, brightness=None, **kwargs) -> None:
             _LOGGER.debug('Unable to turn on light.')
 
     @property
-    def state_attributes(self):
+    def device_state_attributes(self):
         """Flag supported attributes."""
         return {ATTR_BRIGHTNESS: self.value}