ncr5380: Remove redundant register writes

Remove the duplicate write to the Select Enable Register that appeared
in v1.1.38.

Also remove the redundant write to Initiator Command Register prior to
calling do_abort().

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>