cmd/compile: be more conservative about arm64 insns that can take zero register

cmd/compile: be more conservative about arm64 insns that can take zero register

It's really only needed for stores and store-like instructions
(atomic exchange, compare-and-swap, ...).

Fixes #73180

Change-Id: I8ecd833a301355adf0fa4bff43250091640c6226
Reviewed-on: https://go-review.googlesource.com/c/go/+/663155
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>