[llvm] [NFC][SPIRV] Fix for selectExtInst to be able to process intrinsics (PR #110864)

[Farzon Lotfi via llvm-commits]

farzonl wrote:

> Looks good to me. I didn't see any test changes in this PR, so I assume this change will be covered by existing tests?

Yeah nfc so existing tests not breaking for the intrinsic selects replaced is the test to show this works.

https://github.com/llvm/llvm-project/pull/110864