[llvm] [SPIR-V] Ensure that we don't have a dangling BlockAddress constants after internal intrinsic 'spv_switch' is processed (PR #92390)

[Vyacheslav Levytskyy via llvm-commits]

https://github.com/VyacheslavLevytskyy closed https://github.com/llvm/llvm-project/pull/92390