Fix iPad split view (#8199)

* Fix iPad split view

* remove unused type def

libraries/@mattermost/rnutils/ios/RNUtilsWrapper.swift

@@ -5,9 +5,10 @@ import React
     @objc public weak var delegate: RNUtilsDelegate? = nil
     
     deinit {
-        NotificationCenter.default.removeObserver(self,
-           name: NSNotification.Name.RCTUserInterfaceStyleDidChange,
-           object: nil)
+        DispatchQueue.main.async {
+            guard let w = UIApplication.shared.delegate?.window, let window = w else { return }
+            window.removeObserver(self, forKeyPath: "frame")
+        }
     }
     
     func getSharedDirectory() -> URL? {

types/global/device.d.ts

@@ -1,7 +0,0 @@
-// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
-// See LICENSE.txt for license information.
-
-type SplitViewResult = {
-    isSplitView: boolean;
-    isTablet: boolean;
-}