scsi: scsi_error: Do not retry illegal function error

Hitachi USP-V returns 'ILLEGAL FUNCTION' when the internal staging
mechanism encountered an error. These errors should not be retried on
another path.

[mkp: s/invalid/illegal/]

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