staging: lustre: fix bogus lst errors for lnet selftest

It should not be counted as errors if a test RPC
has been stopped due to administrative actions,
e.g. lst end_session from the remote test console.

Signed-off-by: Isaac Huang <he.huang@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4181
Reviewed-on: http://review.whamcloud.com/13279


Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>