[llvm] [llvm-objdump] Eliminate the dependency of `--mcpu=help` and `--mattr=help` on `-d` (PR #165661)

[Ruoyu Qiu via llvm-commits]

cabbaken wrote:

I think the test cases I wrote is like a pile of garbage.
I'm optimizing them and will push a commit soon. Should I convert this PR to a draft?
Additionally, do you think the PR title is suitable for this PR now?

https://github.com/llvm/llvm-project/pull/165661