[llvm] [GISel] Use getScalarSizeInBits in LegalizerHelper::lowerBitCount (PR #168584)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-nvptx64-nvidia-win` running on `as-builder-8` while building `llvm` at step 2 "checkout".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/155/builds/14961

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 2 (checkout) failure: update (failure)
git version 2.41.0.windows.3
remote: Internal Server Error
fatal: unable to access 'https://github.com/llvm/llvm-project.git/': The requested URL returned error: 500
remote: Internal Server Error
fatal: unable to access 'https://github.com/llvm/llvm-project.git/': The requested URL returned error: 500

```

</details>

https://github.com/llvm/llvm-project/pull/168584