When link partner is sending continuous Config symbols, the 82571 Serdes
FIFO can overflow resulting in Invalid bit getting set.  To resolve this,
if Sync and Config bits are both 1 ignore the Invalid bit and restart
auto-negotiation.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>