Spurious nmi button events in log

[ofaurax]

On some hardware, a normal, clean host shutdown (e.g. just running shutdown -h now on the host) results in a bunch of “NMI Button Pressed” entries getting written to the redfish event log, with a “Critical” severity level.
This is likely due to an unstable voltage on some line, during shutdown.

To prevent these "Critical" log, we should check the host status before sending them.

[ofaurax]

Should be fixed by this patch: https://gerrit.openbmc.org/c/openbmc/x86-power-control/+/62761