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

[Damyan Pepper via llvm-commits]

damyanp 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.

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