[llvm] [LegalizeVectorTypes] Preserve original MemoryOperand and MemVT when widening fixed vector load to vp_load. (PR #109473)

[Luke Lau via llvm-commits]

https://github.com/lukel97 approved this pull request.

LGTM, I just quickly checked to see what we do currently and we're increasing the MMO size at least for fixed vectors

```
t5: v3i64,ch = load<(load (s192) from %ir.p, align 32)> t0, t2, undef:i64
```
```
t19: v4i64,ch = vp_load<(load (s256) from %ir.p)> t0, t2, undef:i64, t17, Constant:i64<3>
```

https://github.com/llvm/llvm-project/pull/109473