[clang] [Clang] Refactor diagnostics for SME builtins. (PR #78258)

[Matthew Devereau via cfe-commits]

================
@@ -3005,6 +3005,15 @@ enum ArmStreamingType {
   ArmStreamingOrSVE2p1
 };
 
+enum ArmSMEState : unsigned {
+  ArmNoState = 0,
+
+  ArmInZA = 0b01,
+  ArmOutZA = 0b10,
+  ArmInOutZA = 0b11,
+  ArmZAMask = 0b11,
----------------
MDevereau wrote:

```suggestion
  ArmZAMask = ArmInOutZA,
```

https://github.com/llvm/llvm-project/pull/78258