atari_NCR5380: Merge from NCR5380.c

The NCR5380.c core driver has moved on since the atari_NCR5380.c fork.
Some of those changes are also relevant to atari_NCR5380.c so apply them
there as well.

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>