[llvm] [DXIL] Add DXIL SubArch to correspond to version number (PR #89125)

[S. Bharadwaj Yadavalli via llvm-commits]

bharadwajy wrote:

> > > Is this related to #88885?
> > 
> > 
> > Yes.
> 
> Could you link it to the issue please? Either with a "fixes" note in the description or using the "Development" section on the right.

I linked this branch in "Development" section.

https://github.com/llvm/llvm-project/pull/89125