[llvm] [SPIR-V] Preserve pointer-to-pointer element type for T*& parameters (PR #203113)

[Nick Sarnie via llvm-commits]

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

i am not an expert in this code but i don't see anything that seems questionable given how difficult type deduction is

https://github.com/llvm/llvm-project/pull/203113