Remove superfluous icon and padding that came with sdk 24

Fixes #5965
// FREEBIE

src/org/thoughtcrime/securesms/RecipientPreferenceActivity.java

@@ -130,6 +130,8 @@ public class RecipientPreferenceActivity extends PassphraseRequiredActionBarActi
 
   private void initializeToolbar() {
     this.toolbar = (Toolbar) findViewById(R.id.toolbar);
+    this.toolbar.setLogo(null);
+
     setSupportActionBar(toolbar);
 
     getSupportActionBar().setDisplayHomeAsUpEnabled(true);