macio: remove nonexistent interrupt on pin 1

The current macio implementation declares an interrupt that doesn't appear to
exist in the hardware or any other emulator implementation. OpenBIOS detects
this interrupt and generates an 'interrupts' property in the macio device tree
entry. Mac OS 9 halts boot when it detects this interrupt, so it has been
removed to permit further progress in the boot process.

Signed-off-by: Cormac O'Brien <i.am.cormac.obrien@gmail.com>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Alexander Graf <agraf@suse.de>