Apply implicit fallback seat config

The implicit fallback seat config needs to be applied (if created).
Otherwise, the input devices will still be removed from the implicit
default seat on reload when there is any seat config.

sway/input/input-manager.c

@@ -102,7 +102,8 @@ void input_manager_verify_fallback_seat(void) {
 		seat = input_manager_get_default_seat();
 		struct seat_config *sc = new_seat_config(seat->wlr_seat->name);
 		sc->fallback = true;
-		store_seat_config(sc);
+		sc = store_seat_config(sc);
+		input_manager_apply_seat_config(sc);
 	}
 }