[llvm] [SPIR-V] Fix legalize info for G_BITREVERSE (PR #93699)

[Vyacheslav Levytskyy via llvm-commits]

VyacheslavLevytskyy wrote:

> Drive by nit: Why were there no test changes, when you touched the legalizer?
> It originated from https://reviews.llvm.org/D116464, which is a huge patch with no tests.

@tschuett  Yes, it looks like legalizer wasn't covered by tests properly. It's one of our priorities now to improve test cases.

https://github.com/llvm/llvm-project/pull/93699