scsi: qla2xxx: Defer chip reset until target mode is enabled

For target mode, any chip reset triggered before target mode is enabled will
be held off until user is ready to enable.  This prevents the chip from
starting or running before it is intended.

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>