[llvm] [LV] Check early for supported interleave factors with scalable types [nfc] (PR #111592)

[Mel Chen via llvm-commits]

================
@@ -3414,9 +3415,14 @@ bool LoopVectorizationCostModel::interleavedAccessCanBeWidened(
   if (hasIrregularType(ScalarTy, DL))
     return false;
 
+  // We currently only know how to emit interleave/deinterleave with
+  // Factor=2 for scalable vectors.  This is purely an implementation
----------------
Mel-Chen wrote:

nit
```suggestion
  // Factor=2 for scalable vectors. This is purely an implementation
```

https://github.com/llvm/llvm-project/pull/111592