Fix warning in getting charge level units

src/hardware_battery.cpp

@@ -520,7 +520,7 @@ bool Battery::checkChargeLevelUnit () {
 	TDEBatteryDevice* bdevice = dynamic_cast<TDEBatteryDevice*>(m_hwdevices->findByUniqueID(udi));
 	if (!bdevice) {
 		//grr... no luck
-		kdError() << "Battery::checkChargeLevelRate couldn't find battery" << endl;
+		kdError() << "Battery::checkChargeLevelUnit couldn't find battery" << endl;
 		kdDebugFuncOut(trace);
 		return false;
 	}
@@ -531,11 +531,11 @@ bool Battery::checkChargeLevelUnit () {
 		return false;
 	}
 
-	// FIXME VERIFY CORRECTNESS
-	// what does tdepowersave expect to see in charge_level_unit (battery.charge_level.unit)?
-	charge_level_unit = "wH";
-	//query was not successfull but this is optional
-	kdWarning() << "Couldn't request charge_level.unit for udi: " << udi << endl;
+	// Power supply energy informations in sysfs are always in uWh.
+	// https://www.kernel.org/doc/Documentation/power/power_supply_class.txt
+	// TDE hardware library internally uses Wh.
+	// Since charge level unit are always Wh.
+	charge_level_unit = "Wh";
 	kdDebugFuncOut(trace);
 	return false;
 }