cmd/compile: redo flag constant ops for arm64

Fixes the *noov opcodes so they handle a constant argument properly.

Most of the infrastructure for this CL is in CL 238077 (the arm32 one).

Fixes #39505

Change-Id: Id424a4e18964b848f05aa42f4d78e5f2e2cdf43b
Reviewed-on: https://go-review.googlesource.com/c/go/+/237999


Reviewed-by: Cherry Zhang <cherryyz@google.com>