Mi Band 2: enable third party hr sensor access setting

This works but since the Mi Band 2 has no "status" menu or activities, live activity has
to be started (charts swipe to right), but that spams the database...

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/huami/miband2/MiBand2Coordinator.java

@@ -87,6 +87,7 @@ public class MiBand2Coordinator extends HuamiCoordinator {
                 R.xml.devicesettings_donotdisturb_withauto,
                 R.xml.devicesettings_liftwrist_display,
                 R.xml.devicesettings_rotatewrist_cycleinfo,
+                R.xml.devicesettings_expose_hr_thirdparty,
                 R.xml.devicesettings_pairingkey
         };
     }