[aarch64] VM status remains "running" after it's suspended

The issue is observed on aarch64 (I didn't check x86) with latest upstream QEMU bits. 

Steps to reproduce:

1) start guest

2) suspend guest with this command:

# echo mem > /sys/power/state

  Check console messages, which should indicate that guest has been suspended.

3) check guest status through HMP command "info status":

  (qemu) info status
   info status
   VM status: running

Note it's "running", which is incorrect. 

QEMU version:

# qemu-system-aarch64 --version
QEMU emulator version 3.1.50 (v3.1.0-2203-g9403bcc)
Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers

The issue prevents user from resuming a suspended guest through "system_wakeup" HMP command, because QEMU thinks the guest is in running state and does nothing.

I think the issues occurs because qemu_system_wakeup_request() doesn't get called. It seems the root cause is with ACPI related code.