LU-6503 lnet: info leak in lnet_ping()

This patch is a backport from upstream
751a624adbe47145d3667c4b504858ffd3e8f175

On 64 bit systems there is a 4 byte hole after
the last member of the struct. We should clear
it to avoid disclosing stack information.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Sheng <yang.sheng@intel.com>
Change-Id: I15849b3b35034d6c0c2a0f4c5cd0210ec453084e
Reviewed-on: http://review.whamcloud.com/14706
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Tested-by: Jenkins
Reviewed-by: Isaac Huang <he.huang@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>