Remove stale dependency in "ozone_demo" GN target.

ui/ozone/demo/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 group("demo") {
   deps = [
     ":ozone_demo",
   ]
 }
 
@@ skipping 11 matching lines @@
     "surfaceless_gl_renderer.h",
   ]
 
   deps = [
     "//base",
     "//skia",
     "//ui/events/ozone:events_ozone_layout",
     "//ui/gfx/geometry",
     "//ui/gl",
     "//ui/ozone",
-    "//ui/ozone/gpu",
     "//ui/ozone:ozone_base",
   ]
 }