scsi: qla2xxx: Clear loop id after delete

scsi: qla2xxx: Clear loop id after delete

Clear loop id after delete to prevent session invalidation of stale
session.

Fixes: 726b85487067d ("qla2xxx: Add framework for async fabric discovery")
Cc: <stable@vger.kernel.org> # 4.10+
Signed-off-by: Quinn Tran <quinn.tran@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>