Remove unnecessary converting us to ms

The class "Estimate" has the menber estimateMillis and
the unit of batteryUsageStats.getBatteryTimeRemainingMs() is
millisecond,so converting from us to ms is unnecessary.

Bug: 187379252
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.fuelgauge.BatteryInfoTest
Test: manual
Change-Id: If7c1092c1b7e5f74f8907ffe0248eccf3535ac0c

src/com/android/settings/fuelgauge/BatteryUtils.java

@@ -400,7 +400,7 @@ public class BatteryUtils {
         // couldn't get estimate from cache or provider, use fallback
         if (estimate == null) {
             estimate = new Estimate(
-                    PowerUtil.convertUsToMs(batteryUsageStats.getBatteryTimeRemainingMs()),
+                    batteryUsageStats.getBatteryTimeRemainingMs(),
                     false /* isBasedOnUsage */,
                     EstimateKt.AVERAGE_TIME_TO_DISCHARGE_UNKNOWN);
         }