ixgbe: refactor link setup code

Link code cleanup: a number of redundant functions and MAC variables are cleaned up,
with some functions being consolidated into a single-purpose code path.
Removed following deprecated link functions and mac variables
 * ixgbe_setup_copper_link_speed_82598
 * ixgbe_setup_mac_link_speed_multispeed_fiber
 * ixgbe_setup_mac_link_speed_82599
 * mac.autoneg, mac.autoneg_succeeded, phy.autoneg_wait_to_complete

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>