[llvm] [SelectionDAG][RISCV] Use VP_LOAD to widen MLOAD in type legalization when possible. (PR #140595)

[Luke Lau via llvm-commits]

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

LGTM. Does this need rebased on top of the fixed vector tests?

https://github.com/llvm/llvm-project/pull/140595