ixgbe: Update link setup code to better support autonegotiation of speed

The current code has some flaws in it when performing autonegotiation,
especially on KX/KX4 links.  This patch updates the code to better handle
the autonegotiation states on link setup.  The patch also removes a redundant
link configuration call on driver load, and moves link configuration to
the ->open() path.

Signed-off-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>