platform/x86: asus-wmi: Add support for MCU powersave

Add support for an MCU powersave WMI call. This is intended to set the
MCU in to a low-power mode when sleeping. This mode can cut sleep power
use by around half.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Luke D. Jones <luke@ljones.dev>
Link: https://lore.kernel.org/r/20240404001652.86207-9-luke@ljones.dev


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