[llvm] [GISel] Legalize bitreverse with types smaller than 8 bits (PR #92998)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> > Test the vector cases too?
> 
> IRTranslator haven't supported vector intrinsics yet :( See https://godbolt.org/z/xTfGMfEr3

Maybe something goes wrong for scalable vectors, but vector intrinsics work? 

https://github.com/llvm/llvm-project/pull/92998