[llvm] [LLVM][AArch64] Correctly lower funnel shifts by zero. (PR #140058)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

> getNode() already handles zero shift amounts for shifts and rotates - why not just add it for fshl/fshr as well?

I'll give it a go and see what drops out.

https://github.com/llvm/llvm-project/pull/140058