Vulkan: Limit clampFragDepth workaround to affected drivers Bug: angleproject:3970 Change-Id: I708591d86b8f2cb10d0cbdc7c14518fda45ac626 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4562134 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Alexey Knyazev <lexa.knyazev@gmail.com>