[llvm] [LLVM][CodeGen][SVE] Lower to multivector stores (PR #207397)

[Benjamin Maxwell via llvm-commits]

================
@@ -2107,6 +2106,16 @@ AArch64TargetLowering::AArch64TargetLowering(const TargetMachine &TM,
       setOperationAction(ISD::LOAD, MVT::nxv4f64, Custom);
       setOperationAction(ISD::LOAD, MVT::nxv16bf16, Custom);
 
+      // 2x stores
----------------
MacDue wrote:

nit: We could just do:

```
for (Opcode : {ISD::LOAD, ISD::STORE) {
  // 2x multi-vector loads/stores
   setOperationAction(Opcode, ....);

  // 4x multi-vector loads/stores
   setOperationAction(Opcode, ....);
}
```

To save a little bit of duplication. 

https://github.com/llvm/llvm-project/pull/207397