Level count was off by one for the size.
Also change vk::MAX_IMAGE_ARRAY_LAYERS to be the actual value rather
than log2 -- this was a bug waiting to happen somewhere.

Bug: b/118429780
Change-Id: I783a11571f90c34302a4ead8476009d309880eb6
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/26508Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>