ixgbe: Harden the 82599 multispeed fiber autotry mechanism

82599 supports multispeed fiber optical modules (10Gbps/1Gbps).  Some
scenarios can cause the autotry mechanism to not negotiate link properly.
What needs to happen is the driver must flap the Tx laser to induce an Rx
Loss of Signal on the link partner.  This will restart the autotry
mechanism to get link into a known state.  The software definable pin (SDP)
3 on the 0x10fb NIC is wired to cause a Tx LOS event, which triggers the
Rx LOS we require.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Acked-by: Mallikarjuna R Chilakala <mallikarjuna.chilakala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>