Fix interface validation in Vulkan.

TBR=bsalomon@google.com

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3176

Change-Id: Ifad3249e6839e9b4aa34792646b2d54ff9304da7
Reviewed-on: https://skia-review.googlesource.com/3176
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
3 files changed