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

[Sander de Smalen via llvm-commits]

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@@ -444,6 +444,8 @@ enum NodeType : unsigned {
   // SME
   RDSVL,
   REVD_MERGE_PASSTHRU,
+  EXPAND_ZA_BUFFER,
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sdesmalen-arm wrote:

nit: can we rename 'Expand ZA' to 'Allocate ZA' throughout this PR?

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