staging/lustre/llite: deny non-root user for changelog operations

To avoid potential security problems, non-privileged users should
have no permission to run 'lfs changelog' & 'lfs changelog_clear'.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-on: http://review.whamcloud.com/14280
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6415


Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>