platform/x86: asus-nb-wmi: Add keymap for display toggle

platform/x86: asus-nb-wmi: Add keymap for display toggle

On the Asus Zenbook 14 (UX3405MA), the Fn+F7 key combination emits
WMI code 0x2d, which was previously unmapped.

Map this code to KEY_DISPLAYTOGGLE. This matches the behavior of the
display toggle/projector mode key found on other Asus laptops, allowing
userspace to handle multi-monitor switching or screen toggling.

Tested on ASUS Zenbook 14 UX3405MA.

Signed-off-by: Tim Wassink <timwassink.dev@gmail.com>
Reviewed-by: Denis Benato <benato.denis96@gmail.com>
Link: https://patch.msgid.link/20251221181724.19927-1-timwassink.dev@gmail.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>