[clang] [clang] remove non-functional SrcAddr parameter from performAddrSpaceCast (PR #179330)

[Yaxun Liu via cfe-commits]

yxsamliu wrote:

add @rjmccall for advice.

amdgpu is OK with the change since we only do addrspacecast, but not sure whether there is out-of-tree target does something other than addrspacecast and need the original AST-level src addr space which may be lost in IR due to mapping.

https://github.com/llvm/llvm-project/pull/179330