vkd3d-shader/spirv: Do not declare resources as multisampled if the sample count is 1.

It is illegal to match a SPIR-V multisampled resource to a Vulkan resource which is not multisampled. Vulkan considers a resource to be multisampled if its sample count is greater than 1 (and SPIR-V does not care about the sample count).

This fixes validation errors in the case where the sample count does actually match the resource. In order to provide correct behaviour when there is a mismatch, or when the sample count is missing, we will need yet another additional interface. In the absence of that it seems best to provide a best guess.

This fixes a validation error with the not-yet-committed merge request 135, when the d3d11 runner is run through Wine with the Vulkan backend.