[llvm] [DAG] visitFREEZE - always allow freezing multiple operands (PR #145939)

[Simon Pilgrim via llvm-commits]

================
@@ -3927,6 +3927,7 @@ define void @trunc_v8f16(ptr %x) {
 ; ZVFH-NEXT:    vle16.v v8, (a0)
 ; ZVFH-NEXT:    lui a1, %hi(.LCPI171_0)
 ; ZVFH-NEXT:    flh fa5, %lo(.LCPI171_0)(a1)
+; ZVFH-NEXT:    vmv.v.v v8, v8
----------------
RKSimon wrote:

All of these appear to be due to us replacing:
```
t11: nxv2f32 = insert_subvector undef:nxv2f32, t28, Constant:i32<0>
```
with
```
    t25: nxv2f32 = freeze undef:nxv2f32
  t26: nxv2f32 = insert_subvector t25, t24, Constant:i32<0>
```

https://github.com/llvm/llvm-project/pull/145939