scsi: NCR5380: Always re-enable reselection interrupt

The reselection interrupt gets disabled during selection and must be
re-enabled when hostdata->connected becomes NULL. If it isn't re-enabled a
disconnected command may time-out or the target may wedge the bus while
trying to reselect the host. This can happen after a command is aborted.

Fix this by enabling the reselection interrupt in NCR5380_main() after
calls to NCR5380_select() and NCR5380_information_transfer() return.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: stable@vger.kernel.org # v4.9+
Fixes: 8b00c3d5 ("ncr5380: Implement new eh_abort_handler")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>