staging: lustre: fix conctl.c issues found by Klocwork Insight tool

staging: lustre: fix conctl.c issues found by Klocwork Insight tool

The function lst_test_add_ioctl is always copying lstio_tes_param
from userland even if the user doesn't send this data to LNet
selftest. Only consider lstio_tes_param data if lstio_tes_param_len
is not zero.

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4629
Reviewed-on: http://review.whamcloud.com/9386
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Isaac Huang <he.huang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>