scsi: qla2xxx: Reject EH_{abort|device_reset|target_request}

Reject eh_{abort|device_reset|target_reset} when rport is being torn down
or chip is down.

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