platform/x86: asus-wmi: don't allow eGPU switching if eGPU not connected

Check the ASUS_WMI_DEVID_EGPU_CONNECTED method for eGPU connection
before allowing the ASUS_WMI_DEVID_EGPU method to run.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230630053552.976579-6-luke@ljones.dev


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