[llvm] MCExpr-ify amd_kernel_code_t (PR #91587)

[Janek van Oirschot via llvm-commits]

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@@ -20,6 +21,7 @@ add_llvm_component_library(LLVMAMDGPUDesc
   CodeGenTypes
   Core
   MC
+  MCParser
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JanekvO wrote:

Questioning whether it's desired to have `MCParser` within the `AMDGPUDesc`. Initially seemed suitable to have `AMDGPUMCKernelCodeT` together with `AMDGPUMCKernelDescriptor` as they are both consumers of `SIProgramInfo` and serve a similar metadata emit purpose but it may be desired to have `AMDGPUMCKernelCodeT` elsewhere. Let me know if anybody objects to the `MCParser` and/or would prefer `AMDGPUMCKernelCodeT` to live elsewhere.

https://github.com/llvm/llvm-project/pull/91587