staging/lustre/obdclass: remove unuse variables from lprocfs_stats_collect/clear

This is only part of the original Lustre tree commit splitted to follow the
"one thing per patch" rule.

Lustre-change: http://review.whamcloud.com/6139
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3204


Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>