[clang] [clang][CodeGen] `sret` args should always point to the `alloca` AS, so use that (PR #114062)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> seeing breaks in downstream build of rocPRIM

Probably need to revert the downstream revert of the original problematic patch 

https://github.com/llvm/llvm-project/pull/114062