[clang] [clang][SPIR-V] Fix OpenCL addrspace mapping when using non-zero default AS (PR #137187)

[Nick Sarnie via cfe-commits]

sarnex wrote:

Ah ok thank you! I'm surprised this work effects anything as I was mostly doing it for upstream OMP SPV which doesnt' work yet :)

https://github.com/llvm/llvm-project/pull/137187