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

[Matt Arsenault via llvm-commits]

arsenm wrote:

> @arsenm Can I add some vector tests with `-global-isel-abort=0` as we did in #93063?

Yes, the only thing with those is one day someone will need to go back and remove all the -global-isel-abort=0 flags 

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