Fix bluetooth device forgetting

Bug: 27476922
Change-Id: I8c5b7076a04185371311fb4ff1c1ba0df0df19dc
diff --git a/src/com/android/settings/bluetooth/DeviceListPreferenceFragment.java b/src/com/android/settings/bluetooth/DeviceListPreferenceFragment.java
index 1eea942..e6fcbcb 100644
--- a/src/com/android/settings/bluetooth/DeviceListPreferenceFragment.java
+++ b/src/com/android/settings/bluetooth/DeviceListPreferenceFragment.java
@@ -181,6 +181,7 @@
 
         if (preference == null) {
             preference = new BluetoothDevicePreference(getPrefContext(), cachedDevice);
+            preference.setKey(key);
             mDeviceListGroup.addPreference(preference);
         } else {
             // Tell the preference it is being re-used in case there is new info in the