tests: Fix ImageAspectMask usage for vk_blit_tests operation.

Remove code that forced a single bit in the image aspect masks
which allows tests to work correctly on devices that use
24/8 depth/stencil buffers.
Add checks for proper usage according to spec.

Change-Id: Ie0a5d70c4d5e286f96c2e4376f46ea66a6d82656
diff --git a/tests/vktestbinding.cpp b/tests/vktestbinding.cpp
index 2acb162..8b5ce26 100644
--- a/tests/vktestbinding.cpp
+++ b/tests/vktestbinding.cpp
@@ -598,7 +598,7 @@
 Image::subresource_layout(const VkImageSubresourceLayers &subrescopy) const {
     VkSubresourceLayout data;
     VkImageSubresource subres =
-        subresource(image_aspect(subrescopy.aspectMask), subrescopy.mipLevel,
+        subresource(subrescopy.aspectMask, subrescopy.mipLevel,
                     subrescopy.baseArrayLayer);
     size_t size = sizeof(data);
     vkGetImageSubresourceLayout(device(), handle(), &subres, &data);