removed unused resources

src/main/java/eu/siacs/conversations/ui/ConversationActivity.java

@@ -425,11 +425,7 @@ public class ConversationActivity extends XmppActivity
 			menuAdd.setVisible(!isConversationsOverviewHideable());
 			if (this.getSelectedConversation() != null) {
 				if (this.getSelectedConversation().getNextEncryption() != Message.ENCRYPTION_NONE) {
-					if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
-						menuSecure.setIcon(R.drawable.ic_lock_white_24dp);
-					} else {
-						menuSecure.setIcon(R.drawable.ic_action_secure);
-					}
+					menuSecure.setIcon(R.drawable.ic_lock_white_24dp);
 				}
 				if (this.getSelectedConversation().getMode() == Conversation.MODE_MULTI) {
 					menuContactDetails.setVisible(false);