[clang] [AMDGPU][SPIR-V] Fix treating SPIR-V input as the wrong LLVM-IR (PR #202986)

[Manuel Carrasco via cfe-commits]

mgcarrasco wrote:

Thank you. I missed updating the translator, which fixed the ICE for `-no-use-spirv-backend`.

The only issues that remain are the ones about the warnings:

- `-no-use-spirv-backend --offload-new-driver`
- `-use-spirv-backend --offload-new-driver`

https://github.com/llvm/llvm-project/pull/202986