[llvm] [AMDGPU] Propagate debug info to constant materialization instr (PR #192669)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse commented:

I'm slightly surprised this missing location hasn't been caught up until now; possibly because x86 is able to fold many constants into instructions, it hasn't appeared too often.

One test-update request inline, I don't think it's an error, just a loss of coverage. Otherwise looks good.

https://github.com/llvm/llvm-project/pull/192669