asus-wmi: Add dgpu disable method

In Windows the ASUS Armory Crate program can enable or disable the
dGPU via a WMI call. This functions much the same as various Linux
methods in software where the dGPU is removed from the device tree.

However the WMI call saves the state of dGPU (enabled or not) and
this then changes the dGPU visibility in Linux with no way for
Linux users to re-enable it. We expose the WMI method so users can
see and change the dGPU ACPI state.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
Link: https://lore.kernel.org/r/20210807023656.25020-3-luke@ljones.dev


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