if_link: Add additional parameter to IFLA_VF_INFO for spoof checking

Add configuration setting for drivers to turn spoof checking on or off
for discrete VFs.

v2 - Fix indentation problem, wrap the ifla_vf_info structure in
     #ifdef __KERNEL__ to prevent user space from accessing and
     change function paramater for the spoof check setting netdev
     op from u8 to bool.
v3 - Preset spoof check setting to -1 so that user space tools such
     as ip can detect that the driver didn't report a spoofcheck
     setting.  Prevents incorrect display of spoof check settings
     for drivers that don't report it.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>