[Wi-Fi] Fix MAC address title information display bug

Use WifiTrackerLib, we can use WifiEntry.getPrivacy()
to get the value for a Passpoint network.

Bug: 159672621
Test: manual visual
      Switch Privacy setting in Wi-Fi detail page, observe
      MAC address title.
Change-Id: I5411e727c5f48dc0d65a05706194569ca3bbebdc