scsi: qla2xxx: Fix NPIV host cleanup in target mode

Add check to make sure we are cleaning up global target host list only
for NPIV hosts

Fixes: bdbe24de ("scsi: qla2xxx: Cleanup NPIV host in target mode during config teardown")
Cc: <stable@vger.kernel.org> # 4.10+
Signed-off-by: Sawan Chandak <sawan.chandak@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>