[llvm] [TableGen] Diagnose sub-register indices that overflow their register (PR #206346)

[Taimuraz Kaitmazov via llvm-commits]

atassis wrote:

@jurahul  Hi! Thanks for a review again.
I have no access to merge this on my behalf, can I ask you to merge the PR? Or smth else should be done by me?

https://github.com/llvm/llvm-project/pull/206346