[llvm] [AArch64][SME] Remove unused ZA lazy-save (PR #81648)

[Kerry McLaughlin via llvm-commits]

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@@ -35,6 +35,11 @@ struct AArch64FunctionInfo;
 class AArch64Subtarget;
 class MachineInstr;
 
+struct TPIDR2Object {
+  unsigned FrameIndex = 0;
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kmclaughlin-arm wrote:

I've found that other places which initialise a frame index use `std::numeric_limits<int>::max()`, so I think it's safer to use this here as well (e.g. see `SwiftAsyncContextFrameIdx`).

https://github.com/llvm/llvm-project/pull/81648