[llvm] [AArch64][SME] Enable dynamic shuffle for fixed length types. (PR #72490)

[Sander de Smalen via llvm-commits]

https://github.com/sdesmalen-arm commented:

Looks mostly fine to me, with some nits I'd like you to address before landing the patch.

Suggestion on the commit message: it says "SME" but should this be "SVE2"?

https://github.com/llvm/llvm-project/pull/72490