ocs_fc: When commands complete with an error, freeze the device queue.

Proper error recovery depends on freezing the device queue when an
error occurs, so we can recover from an error before sending
additional commands.

The ocs_fc(4) driver was not freezing the device queue for most
SCSI errors, and that broke error recovery.

sys/dev/ocs_fc/ocs_cam.c:
In ocs_scsi_initiator_io_cb(), freeze the device queue if

we're passing back status other than CAM_REQ_CMP.

Submitted by: ken@kdm.org
Reviewed by: mav, ken