Use the speedometer icon in the fastdotcom sensor (#12348)

This change makes the icon match the one used in the speedtest sensor.

homeassistant/components/sensor/fastdotcom.py

@@ -26,6 +26,8 @@ CONF_HOUR = 'hour'
 CONF_DAY = 'day'
 CONF_MANUAL = 'manual'
 
+ICON = 'mdi:speedometer'
+
 PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
     vol.Optional(CONF_SECOND, default=[0]):
         vol.All(cv.ensure_list, [vol.All(vol.Coerce(int), vol.Range(0, 59))]),
@@ -94,6 +96,11 @@ class SpeedtestSensor(Entity):
             return
         self._state = state.state
 
+    @property
+    def icon(self):
+        """Return icon."""
+        return ICON
+
 
 class SpeedtestData(object):
     """Get the latest data from fast.com."""