parametrize FileImportCache for filename

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentService.java

@@ -477,7 +477,7 @@ public class KeychainIntentService extends IntentService
                 } else {
                     // get entries from cached file
                     FileImportCache<ParcelableKeyRing> cache =
-                            new FileImportCache<ParcelableKeyRing>(this);
+                            new FileImportCache<ParcelableKeyRing>(this, "key_import.pcl");
                     entries = cache.readCacheIntoList();
                 }