ncr5380: Remove ENABLE_IRQ/DISABLE_IRQ macros

atari_NCR5380.c enables its IRQ when it is already enabled. Sun3 doesn't
use the ENABLE_IRQ/DISABLE_IRQ cruft. Remove it.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>