I tested this with libinput-debug-events(1). Without the patch, the key doesn't produce any event (evdev_scancode2key() returns 0 for a scancode of 0x56). With the patch, the scancode is "converted" to 0x56 (KEY_102ND) and an event is fired. The key is now usable in a evdev/libinput-enabled X.Org server.