powermanagement: Fix log message formatting

Printing out QString takes care of adding both spaces and double quotes.
Otherwise, it used to be like this:

    Data for ' "Battery1" ' not found

dataengines/powermanagement/powermanagementengine.cpp

@@ -469,7 +469,7 @@ bool PowermanagementEngine::sourceRequestEvent(const QString &name)
             updatePowerProfileHolds(reply.value());
         });
     } else {
-        qDebug() << "Data for '" << name << "' not found";
+        qDebug() << "Data for" << name << "not found";
         return false;
     }
     return true;