ixgbe: fix link status check for copper X550em

Read the PHY register twice in order to get the correct value for
autoneg_status.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>