ixgbe: Fix isues while reporting 8259x backplane link capabilities

Fix ethtool get_settings logic to report 10G & 1G advertised and
supported link modes in all 8259x 10G backplane connection types
except for 82598EB BX network connection type.

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