[llvm] [AMDGPU] Add i1 mul patterns (PR #67291)

[Jay Foad via llvm-commits]

jayfoad wrote:

> > > Add i1 mul patterns
> > 
> > 
> > Next time please remember to update the desciption when you rewrite the patch!
> 
> Sorry, I completely forgot. Should I revert & reland with a better name?

No problem, it happens. There is no need to revert the patch.

https://github.com/llvm/llvm-project/pull/67291