Reverts #140730 - that turned out not to be an NFC as we originally
thought. See the attached test for an example. Many thanks to @Garra1980
for reporting!
Note, without this change, the newly added test would be incorrectly
converted to:
```mlir
func.func @view_memref_as_rank0(%arg0: index, %arg1: memref<2xi8>) {
%0 = llvm.mlir.poison : !llvm.struct<(ptr, ptr, i64)>
return
}
```
dca74f794a