[llvm] [GlobalISel] Handle div-by-pow2 (PR #83155)

[Pierre van Houtryve via llvm-commits]

https://github.com/Pierre-vh commented:

Code LGTM but I will leave final approval to others as I don't know about this DIV combine in particular, so I can't verify that the ISA is correct

https://github.com/llvm/llvm-project/pull/83155