Metal: Upload IOSurface data with staging buffers on AMD Crashes have been seen in the AMD driver when locking IOSurfaces. Avoid this by always using a staging buffer and doing a GPU-GPU copy for uploading client side data to IOSurfaces. Bug: angleproject:7573 Change-Id: I4d981a24554a755a7248199699b486d98cbad83d Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3915180 Commit-Queue: Kenneth Russell <kbr@chromium.org> Reviewed-by: Gregg Tavares <gman@chromium.org>