[SCSI] qla2xxx: Fix crash during firmware dump procedure.

System crashes, in initiator mode operation, with
qla2xxx_copy_atioqueues() in stack trace when firmware dump is
attempted.

Check for atio_q_length alone does not indicate if atio_ring is
allocated, make explicit check of atio_ring to avoid the crash.

Applicable to ISP24xx, ISP25xx, ISP81xx & ISP83xx line of HBAs.

Signed-off-by: Arun Easi <arun.easi@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>