[clang] [HLSL] Do not remove `HLSLVkBindingAttr` if the target is not SPIR-V (PR #161752)

[Steven Perron via cfe-commits]

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s-perron wrote:

This is now incorrect. If there is a VkBinding, but we are targeting DXIL, then this is not explicit.

https://github.com/llvm/llvm-project/pull/161752