[llvm] [AMDGPU] Add mark last scratch load pass (PR #75512)

[Mirko Brkušanin via llvm-commits]

mbrkusanin wrote:

> @mbrkusanin ,
> 
> the `LLVM::vgpr-mark-last-scratch-load.mir` test gets failed on the expensive check builders here
> 
>     * https://lab.llvm.org/buildbot/#/builders/104/builds/15165
> 
>     * https://lab.llvm.org/buildbot/#/builders/16/builds/59785
> 
>     * https://lab.llvm.org/buildbot/#/builders/42/builds/12998

https://github.com/llvm/llvm-project/pull/78687

https://github.com/llvm/llvm-project/pull/75512