[clang] [llvm] [AMDGPU] Extend readlane, writelane and readfirstlane intrinsic lowering for generic types (PR #89217)

[Matt Arsenault via cfe-commits]

https://github.com/arsenm requested changes to this pull request.

@jayfoad's testcase fails and the same test should be repeated for all 3 intrinsics 

https://github.com/llvm/llvm-project/pull/89217