ixgbe: Ping the VFs on link status change to trigger link change

When the link status changes on the PF we need to notify the VFs. In order
to do this we should ping all of the VFs in order to trigger a link status
change on them as well.

This fixes issues in which the PF would reset, but the VF didn't because the
NAK flag was not set in the VF mailbox.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>