platform/x86: think-lmi: Add pending_reboot support

The Think-lmi driver was missing pending_reboot support as it wasn't
available from the BIOS. Turns out this is really useful to have from
user space so implementing from a purely SW point of view.

Thanks to Mario Limonciello for guidance on how fwupd would use this.

Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mark Pearson <markpearson@lenovo.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210628222846.8830-1-markpearson@lenovo.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>