scsi: scsi_dh_alua: Check for negative result value

scsi_execute() will now return a negative error if there was an error prior
to command submission; evaluate that instead if checking for DRIVER_ERROR.

[mkp: build fix]

Link: https://lore.kernel.org/r/20210427083046.31620-6-hare@suse.de


Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>