Fixed some plugin usages of self._bus.

Now `_bus` is a common property shared by all the plugins, so it
shouldn't be overloaded.

platypush/plugins/sensor/bme280/__init__.py

@@ -72,7 +72,7 @@ class SensorBme280Plugin(SensorPlugin):
 
         super().__init__(**kwargs)
         self.port = port
-        self._bus = None
+        self._smbus = None
         self._device = None
 
     def _get_device(self):
@@ -82,8 +82,8 @@ class SensorBme280Plugin(SensorPlugin):
         if self._device:
             return self._device
 
-        self._bus = SMBus(self.port)
-        self._device = BME280(i2c_dev=self._bus)
+        self._smbus = SMBus(self.port)
+        self._device = BME280(i2c_dev=self._smbus)
         return self._device
 
     @action

platypush/plugins/zigbee/mqtt/__init__.py

@@ -18,8 +18,6 @@ from typing import (
 
 import paho.mqtt.client as mqtt
 
-from platypush.bus import Bus
-from platypush.context import get_bus
 from platypush.entities import (
     DimmerEntityManager,
     Entity,
@@ -2163,13 +2161,6 @@ class ZigbeeMqttPlugin(
 
         return handler
 
-    @property
-    def _bus(self) -> Bus:
-        """
-        Utility property for the bus.
-        """
-        return get_bus()
-
     def _process_state_message(self, client: MqttClient, msg: str):
         """
         Process a state message.