q800: add alias for MacOS toolbox ROM at 0x40000000

q800: add alias for MacOS toolbox ROM at 0x40000000

According to the Apple Quadra 800 Developer Note document, the Quadra 800 ROM
consists of 2 ROM code sections based at offsets 0x0 and 0x800000. A/UX attempts
to access the toolbox ROM at the lower offset during startup, so provide a
memory alias to allow the access to succeed.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-ID: <20231004083806.757242-20-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>