[llvm] [AArch64][SME] Conditionally do smstart/smstop (PR #77113)

[Sander de Smalen via llvm-commits]

================
@@ -1291,8 +1291,8 @@ class AArch64TargetLowering : public TargetLowering {
 
   // Returns the runtime value for PSTATE.SM. When the function is streaming-
   // compatible, this generates a call to __arm_sme_state.
----------------
sdesmalen-arm wrote:

```suggestion
  // Returns the runtime value for PSTATE.SM by generating a call to __arm_sme_state.
```

https://github.com/llvm/llvm-project/pull/77113