ixgbe: add device to MDIO speed setting

This shouldn't matter as nothing should be attached still to be
consisted control MDIO speed for these devices as well.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>