[AArch64] Don't emit Neon in streaming[-compatible] functions with -fzero-call-used-regs (#116995)

Previously, with `-fzero-call-used-regs` clang/LLVM would incorrectly
emit Neon instructions in streaming functions, and streaming-compatible
functions without SVE.

With this change:

* In streaming functions, Z/p registers will be zeroed
* In streaming compatible functions w/o SVE, D registers will be zeroed
  - (As Neon vector instructions are illegal including `movi v..`)