next-cube: add empty slots for unknown accesses to next.scr memory region

next-cube: add empty slots for unknown accesses to next.scr memory region

The next.scr memory is now effectively unused, however there are 3 separate region
accesses still logged that occur when booting a NeXTStep disk image. Use the
empty_slot device to capture and ignore memory accesses to these 3 memory regions.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Thomas Huth <huth@tuxfamily.org>
Message-ID: <20241222130012.1013374-15-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Thomas Huth <huth@tuxfamily.org>