fix(fan): exclude 0 in explicit speed mappings when calculating step

Comment on #5423

custom_components/tuya_local/fan.py

@@ -154,7 +154,7 @@ class TuyaLocalFan(TuyaLocalEntity, FanEntity):
         if self._speed_dps is None:
             return None
         if self._speed_dps.values(self._device):
-            return 100 / len(self._speed_dps.values(self._device))
+            return 100 / len(v for v in self._speed_dps.values(self._device) if v)
         r = self._speed_dps.range(self._device)
         scale = 100 / r[1] if r else 1.0
         return self._speed_dps.step(self._device) * scale