rtnetlink: Fix VF IFLA policy

Add VF spoof check to IFLA policy.  The original patch I submitted to
add the spoof checking feature to rtnl failed to add the proper policy
rule that identifies the data type and len.  This patch corrects that
oversight.  No bugs have been reported against this but it may cause
some problem for the netlink message parsing that uses the policy
table.

CC: stable@vger.kernel.org
Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>