[clang] [lld] [llvm] AMDGPU: Remove xnack and sramecc subtarget features (PR #212792)

[Scott Linder via cfe-commits]

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slinder1 wrote:

```suggestion
  return getNumExtraSGPRs(STI, VCCUsed, FlatScrUsed, hasXNACK(STI));
```

https://github.com/llvm/llvm-project/pull/212792