ncr5380: Standardize reselection handling

Bring the two NCR5380_reselect() implementations into agreement.

Replace infinite loops in atari_NCR5380.c with timeouts, as per NCR5380.c.

Remove 'abort' flag in NCR5380.c as per atari_NCR5380.c -- if reselection
fails, there may be no MESSAGE IN phase so don't attempt data transfer.

During selection, don't interfere with the chip registers after a
reselection interrupt intervenes.

Clean up some trivial issues with code style, comments and printk.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>