system_powerdown only works once
Description of problem:
When the guest is configured to sleep on power button events, something in the ACPI states are not restored coming out of resume.  The first call to `system_powerdown` succeeds, but the second after waking the system is rejected in `acpi_pm1_evt_power_down()` since `ar->pm1.evt.en` is zero coming out of the resume path.

There is probably something deeper (or perhaps in seabios?) since removing the test in that handler doesn't cause a second sleep either.
Steps to reproduce:
![image](/uploads/60876bde4027c42699f2edf936bd874d/image.png)
1. Boot a guest configured to sleep when it receives a power button event
2. `system_powerdown` from the monitor to tell it to sleep
3. `info status` to verify that it is suspended
4. Wake the guest, either with `system_wakeup` or moving the mouse or something
5. `system_powerdown` has no effect
Additional information:
This is using qemu-7.2.0 built from source with a Windows 10 guest and IGD GPU+audio passthrough.