[Graphite] Fix Graphite Vk depth stencil.

Change-Id: I601659631e777060fa8f9c240978bb815cf1f4b4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/755598
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
2 files changed