[llvm] Reland "[AArch64][SME] Split SMECallAttrs out of SMEAttrs" (PR #138671)

[Sander de Smalen via llvm-commits]

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

Left a few very minor nits, but I think this is a great improvement. Thanks for making this change!

https://github.com/llvm/llvm-project/pull/138671