[llvm] [AMDGPU]: Rewrite mbcnt_lo/mbcnt_hi to work item ID where applicable (PR #160496)

[Teja Alaghari via llvm-commits]

TejaX-Alaghari wrote:

Hi @jmmartinez, I've implemented all the suggestions you've mentioned above.
Apologies for the delay in not getting back sooner. Been gone on a vacation.

Whenever you get some time, please review and let me know if any further enhancements can be made. Thanks!

https://github.com/llvm/llvm-project/pull/160496