staging: lustre: fix 'copy into fixed size buffer' errors

Fix 'copy into fixed size buffer' defects found by Coverity
version 6.0.3:
Copy into fixed size buffer (STRING_OVERFLOW)
The fixed-size string might be overrun by copying without
checking the length.

Signed-off-by: Sebastien Buisson <sebastien.buisson@bull.net>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2074
Reviewed-on: http://review.whamcloud.com/4154


Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>