sns: power factor fixes (#2303)

* Update PZEM004TV30Sensor.h

See table above for the correct scale

* Power factor has no unit

code/espurna/sensors/BaseSensor.h

@@ -95,8 +95,7 @@ class BaseSensor {
             switch (type(index)) {
                 case MAGNITUDE_TEMPERATURE:
                     return sensor::Unit::Celcius;
-                case MAGNITUDE_HUMIDITY:
-                case MAGNITUDE_POWER_FACTOR:
+		case MAGNITUDE_HUMIDITY:
                     return sensor::Unit::Percentage;
                 case MAGNITUDE_PRESSURE:
                     return sensor::Unit::Hectopascal;

code/espurna/sensors/PZEM004TV30Sensor.h

@@ -402,7 +402,7 @@ class PZEM004TV30Sensor : public BaseEmonSensor {
 
         // - Power Factor: 2 bytes in 0.1% (we return %)
         _power_factor = take_2();
-        _power_factor /= 10.0;
+        _power_factor /= 100.0;
 
         // - Alarms: 2 bytes, (NOT IMPLEMENTED)
         // XXX: it seems it can only be either 0xffff or 0 for ON and OFF respectively