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
2 files changed