[llvm] Nvptx port LowerBITCAST to SelectionDAG (PR #120903)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

You'd be better off including all the test changes in the PR instead of having the CI fail - then reviewers can better advise on what you need to do

https://github.com/llvm/llvm-project/pull/120903