Updater: Don't show thousands of days

* When pausing and resuming, the ETA calculation is off by a lot
  due to the time diff since the last calculation resulting in a
  big delta and therefore a very low speed
* By fixing this, we also need to set the last byte count to the total
  byte count there, otherwise the downloaded bytes since last calculation
  will be larger than in reality, resulting in too fast speeds calculated

Change-Id: Ica1053cc297ff59221ea2bc0014f20973a080c88