Ozone-DRM: Remove DCHECK for buffer usage in CreateNativePixmap

dma-buf memory mapping is supported upstream, so there is no longer any
need to check for this on non-ChromeOS platforms.

Bug: b/72096671
Test: Ran on non-ChromeOS device and ensured DCHECK isn't hit.
Change-Id: Id0a1d35207c40167dfa765c89d4e75db79f171f6
Reviewed-on: https://chromium-review.googlesource.com/1012142Reviewed-by: Alex Sakhartchouk <alexst@chromium.org>
Commit-Queue: Daniel Nicoara <dnicoara@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550639}

ui/ozone/platform/drm/gpu/gbm_surface_factory.cc

@@ -144,12 +144,6 @@ scoped_refptr<gfx::NativePixmap> GbmSurfaceFactory::CreateNativePixmap(
     gfx::Size size,
     gfx::BufferFormat format,
     gfx::BufferUsage usage) {
-#if !defined(OS_CHROMEOS)
-  // Support for memory mapping accelerated buffers requires some
-  // CrOS-specific patches (using dma-buf mmap API).
-  DCHECK(gfx::BufferUsage::SCANOUT == usage);
-#endif
-
   scoped_refptr<GbmBuffer> buffer =
       drm_thread_proxy_->CreateBuffer(widget, size, format, usage);
   if (!buffer.get())