Fixes: #18070
Also added a test in: cmd/asm/internal/asm/testdata/arm64.s

Change-Id: Icc43ff7383cc06b8eaccabd9ff0aefa61c4ecb88
Reviewed-on: https://go-review.googlesource.com/33595
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>