scsi: qla2xxx: Cleanup NPIV host in target mode during config teardown

When we tear down the NPIV host configuration in target mode, the
qla_tgt struct was left dangling on the global list. This patch cleans
up link list and frees memory.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>