scsi: scsi_dh_alua: skip RTPG for devices only supporting active/optimized

For hardware only supporting active/optimized there's no point in ever
re-issuing RTPG as the only new state we can possibly read is
active/optimized.  This avoid spurious errors during path failover on
such arrays.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>