[llvm] [AMDGPU] Handle negated f16 and fp conversion DAG combines (PR #213202)

[via llvm-commits]

HalfBloodPrince010 wrote:

> Can you rebase this so the first commit in the PR adds the tests generated with the baseline checks, and then the diff that demonstrates the patch does anything is in the second commit

Done, I have rebased the changes.

First commit adds the baseline tests/checks, and second commit has my changes along with the updated check.

https://github.com/llvm/llvm-project/pull/213202