[llvm] [NFC] Add assert to validate `Objects` list for `HwModeSelect` (PR #123794)

[Rahul Joshi via llvm-commits]

jurahul wrote:

> Does this give a better user experience than the existing check in `HwModeSelect::HwModeSelect`?

I didn't realize that the check was already there. I suspect it does not. With the assert, we are reusing the existing machinery in TableGen to do the check, whereas the existing check is custom code. May be its possible to consolidate the assert into the TableGen HWModeSelect class to prevent duplication and then delete the CPP one?

https://github.com/llvm/llvm-project/pull/123794