HID: asus: listen to the asus-wmi brightness device instead of creating one

HID: asus: listen to the asus-wmi brightness device instead of creating one

Some ROG laptops expose multiple interfaces for controlling the
keyboard/RGB brightness. This creates a name conflict under
asus::kbd_brightness, where the second device ends up being
named asus::kbd_brightness_1 and they are both broken.

Therefore, register a listener to the asus-wmi brightness device
instead of creating a new one.

Reviewed-by: Luke D. Jones <luke@ljones.dev>
Reviewed-by: Benjamin Tissoires <bentiss@kernel.org>
Reviewed-by: Denis Benato <benato.denis96@gmail.com>
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
Link: https://patch.msgid.link/20260122075044.5070-9-lkml@antheas.dev
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>