Avoid hardware echo cancellation for Fairphone FP2

The issue has as been confirmed by me with the stock ROM as of November
2018, and other users have complained for almost 18 months, see
https://forum.fairphone.com/t/fnord/28849 and
https://bugtracker.fairphone.com/project/fairphone-fairphone-os-android-6/issue/77

src/org/thoughtcrime/securesms/ApplicationContext.java

@@ -259,6 +259,7 @@ public class ApplicationContext extends MultiDexApplication implements Dependenc
         add("Mi A1");
         add("E5823"); // Sony z5 compact
         add("Redmi Note 5");
+        add("FP2"); // Fairphone FP2
       }};
 
       Set<String> OPEN_SL_ES_WHITELIST = new HashSet<String>() {{