scsi: qla2xxx: Optimize NPIV tear down process

In the case of NPIV port is being torn down, this patch will set a flag to
indicate VPORT_DELETE. This would prevent relogin to be triggered.

Link: https://lore.kernel.org/r/20190912180918.6436-5-hmadhani@marvell.com
Signed-off-by: Quinn Tran <qutran@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>