EX-1873 iokit: fix the obsolete usage of cfg_device

EX-1873 iokit: fix the obsolete usage of cfg_device

The LCTL command "cfg_device" is obsolete and some operations
(such as "cleanup", "detach") don't support it anymore.
In mds_survey and lfsck-performance it causes the echo client
device not to be destroyed and causes LBUG when umounting the
related Lustre device.

Lustre-change: https://review.whamcloud.com/40227
Lustre-commit: 2e6342a7365825091d9c7b25418033c02ecfbb12

Change-Id: If7f6eff080906e395023289652fcd2a78dfb6fb7
Signed-off-by: Hongchao Zhang <hongchao@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/40227
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/45879
Tested-by: Maloo <maloo@whamcloud.com>