LU-15357 iokit: fix the obsolete usage of cfg_device

LU-15357 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The LCTL command "cfg_device" is obsolete and some operations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.

Change-Id: If7f6eff080906e395023289652fcd2a78dfb6fb7
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/45872
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Colin Faber <cfaber@ddn.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>