[llvm] [llvm-mca] Teach MCA constant registers do not create dependencies (PR #89387)

[Rin Dobrescu via llvm-commits]

Rin18 wrote:

I'm really thankful for the comments I've received so far, I think I've addressed them all. This patch should be in a good state now. Further reviews would be appreciated to move this closer to being merged.

https://github.com/llvm/llvm-project/pull/89387