MacOS 9 is racy when it comes to accessing the shift register. Fix this by
introducing a small delay between data accesses and raising the SR_INT
interrupt bit.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>