platform/x86: asus-wmi: support toggling POST sound

Add support for toggling the BIOS POST sound on some ASUS laptops.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Luke D. Jones <luke@ljones.dev>
Link: https://lore.kernel.org/r/20240404001652.86207-5-luke@ljones.dev


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