ixgbe: fix MNG FW support when adapter not up

We were only turning the laser on when the adapter was up.  This
causes issues for those who wanted to access the MNG FW while the
port was in a down state.  This patch makes sure the laser is turned
on in probe and remain up even after the port is brought down.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>