platform/x86: wmi: Stop using ACPI device class

platform/x86: wmi: Stop using ACPI device class

When an ACPI netlink event is received by acpid, the ACPI device
class is passed as its first argument. But since the class string
is not initialized during probe, an empty string is being passed:

	netlink:  PNP0C14:01 000000d0 00000000

Fix this by passing a static string instead.

Tested on a Dell Inspiron 3505.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240130221942.2770-1-W_Armin@gmx.de
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>