[llvm] [X86] Combine `store + vselect` to `masked_store` (PR #145176)

[Abhishek Kaushik via llvm-commits]

abhishek-kaushik22 wrote:

> Can we use a pattern match instead?

There was no `m_Load` to match the Load, so I've added one.

https://github.com/llvm/llvm-project/pull/145176