[llvm] [AArch64][SME]Check streaming mode when using SME2 instruction in fra… (PR #109680)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

For most code, isStreaming() is the correct check, but I think the generated code here run before we switch into streaming mode.

https://github.com/llvm/llvm-project/pull/109680