[llvm] [AARCH64] Add assembly/disassembly for FMMLA instructions (PR #113313)

[via llvm-commits]

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@@ -8929,15 +8905,15 @@ class sve_fp_matrix_mla<bit sz, string asm, ZPRRegOp zprty>
 
   let Constraints = "$Zda = $_Zda";
   let DestructiveInstType = DestructiveOther;
-  let ElementSize = zprty.ElementSize;
+  let ElementSize = reg_ty.ElementSize;
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SpencerAbson wrote:

```suggestion
  let ElementSize = zda_ty.ElementSize;
```
I believe the `ElementSize` of the `MOVPRFX` should be that of the destination register. That said, I'm not sure it really matters in this case if `FMMLA` can only be followed by an unpredicated `MOVPRFX`?

https://github.com/llvm/llvm-project/pull/113313