No not judge sign in state by display name

app/src/main/java/com/hippo/ehviewer/client/EhUtils.java

@@ -116,8 +116,7 @@ public class EhUtils {
     }
 
     public static boolean hasSignedIn(Context context) {
-        return EhApplication.getEhCookieStore(context).hasSignedIn() &&
-                Settings.getDisplayName() != null;
+        return EhApplication.getEhCookieStore(context).hasSignedIn();
     }
 
     public static String getSuitableTitle(GalleryInfo gi) {