In vulkan tests, use vkGetInstanceProcAddr to get vkGetDeviceProcAddr.

We've run into drivers a few times now that have bugs where they only
expose vkGetInstaneProcAddr and not vkGetDeviceProcAddr. The latest
being swiftshader (which is getting fixed). To avoid this issue in the
future we can just have our tests use vkGetInstanceProcAddr to get
vkGetDeviceProcAddr.

Change-Id: I6d73abde507519c145b873042393f50ce6c4527c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/494822
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
12 files changed