staging: lustre: do not memset after LIBCFS_ALLOC

LIBCFS_ALLOC already zero out the memory allocated, so there is no
need to zero out the memory again.

Signed-off-by: Frank Zago <fzago@cray.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5304
Reviewed-on: http://review.whamcloud.com/11012


Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
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>